CN116828966A

CN116828966A - Optical device

Info

Publication number: CN116828966A
Application number: CN202310297871.3A
Authority: CN
Inventors: 山根健量; 柴田哲也; 水野友人; 福泽英明
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 2022-03-28
Filing date: 2023-03-24
Publication date: 2023-09-29

Abstract

The invention provides a novel optical device. The optical device includes a magnetic element and a light irradiation unit that irradiates light to the magnetic element, wherein the magnetic element includes a first ferromagnetic layer to which light is irradiated, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and magnetization of the first ferromagnetic layer is inclined with respect to either an in-plane direction in which the first ferromagnetic layer expands and a plane perpendicular direction orthogonal to a plane in which the first ferromagnetic layer expands in a state in which light is not irradiated from the light irradiation unit to the magnetic element.

Description

Optical device

Technical Field

The present invention relates to optical devices.

Background

The photoelectric conversion element can be used for various purposes.

For example, patent document 1 describes a receiving device that receives an optical signal using a photodiode. The photodiode is, for example, a pn junction diode using a pn junction of a semiconductor, and converts light into an electric signal.

Patent document 2 describes, for example, a photosensor using a pn junction of a semiconductor and an image sensor using the photosensor.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2001-292107

Patent document 2: U.S. Pat. No. 9842874 Specification

Disclosure of Invention

An optical device using a pn junction of a semiconductor is widely used, but a new optical device needs to be developed for further development. In addition, an optical device capable of detecting the intensity of the irradiated light in a wide intensity range is required.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a novel optical device capable of detecting the intensity of light in a wide intensity range.

In order to solve the above problems, the following means are provided.

(1) The optical device according to the first aspect includes a magnetic element and a light irradiation portion that irradiates light to the magnetic element, the magnetic element includes a first ferromagnetic layer to which light is irradiated, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and magnetization of the first ferromagnetic layer is inclined with respect to either one of an in-plane direction in which the first ferromagnetic layer expands and a plane perpendicular direction orthogonal to a plane in which the first ferromagnetic layer expands in a state in which light is not irradiated from the light irradiation portion to the magnetic element.

(2) In the optical device according to the above aspect, the optical device may further include a magnetic field applying portion that applies a magnetic field to the first ferromagnetic layer, the magnetic field applying portion being located so as not to block light irradiated from the light irradiating portion to the magnetic element.

(3) In the optical device according to the above aspect, the light from the light irradiation unit may not be irradiated to the magnetic field application unit.

(4) In the optical device according to the above aspect, the magnetic element may further include an antiferromagnetic layer in contact with a second surface of the first ferromagnetic layer opposite to the first surface in contact with the spacer layer.

(5) In the optical device according to the above aspect, the antiferromagnetic layer may include an oxide.

(6) In the optical device according to the above aspect, the optical device may further include a piezoelectric element that applies stress to the first ferromagnetic layer.

(7) In the optical device according to the above aspect, the piezoelectric element may be positioned so as not to block light emitted from the light emitting unit to the magnetic element.

(8) In the optical device according to the above aspect, the aspect ratio of the length of the first ferromagnetic layer in the longitudinal direction divided by the length of the first ferromagnetic layer in the lateral direction may be greater than 1 when viewed from the plane perpendicular direction.

(9) The optical device according to the second aspect includes a magnetic element and a light irradiation unit that irradiates light to the magnetic element, wherein the magnetic element includes a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and an RH curve indicating a change in resistance of the magnetic element with respect to an external magnetic field applied to the optical device does not exhibit hysteresis in a state where light is not irradiated from the light irradiation unit to the magnetic element at least in a range including an external magnetic field intensity of zero.

(10) The optical device according to the third aspect includes a magnetic element and a light irradiation portion that irradiates light to the magnetic element, the magnetic element includes a first ferromagnetic layer to which light is irradiated, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and the magnetic domain structure of the first ferromagnetic layer has a vortex structure in a state in which light is not irradiated from the light irradiation portion to the magnetic element.

The optical device of the above-described mode works on a new principle and can detect the intensity of light in a wide intensity range.

Drawings

Fig. 1 is a perspective view of an optical device of a first embodiment.

Fig. 2 is a cross-sectional view of the light detecting element of the first embodiment.

Fig. 3 is a graph showing a relationship between an intensity change of light irradiated to the magnetic element of the first embodiment and a resistance value of the magnetic element.

Fig. 4 is a graph showing an RH curve of the magnetic element according to the first embodiment.

Fig. 5 is a graph showing an RH curve of the magnetic element of the comparative example.

Fig. 6 is a graph showing a relationship between an intensity change of light irradiated to the magnetic element of the comparative example and a resistance value of the magnetic element of the comparative example.

Fig. 7 is a cross-sectional view of a light detecting element of the first modification.

Fig. 8 is a cross-sectional view of a light detecting element of the second embodiment.

Fig. 9 is a cross-sectional view of a light detecting element of a third embodiment.

Fig. 10 is a sectional view of a first state of the light detecting element of the third embodiment.

Fig. 11 is a sectional view of a second state of the light detecting element of the third embodiment.

Fig. 12 is a cross-sectional view of a light detecting element of the fourth embodiment.

Fig. 13 is another cross-sectional view of the light detecting element of the fourth embodiment.

Fig. 14 is a sectional view of a light detecting element of the fifth embodiment.

Fig. 15 is a cross-sectional view of a light detecting element of the sixth embodiment.

Fig. 16 is another cross-sectional view of the light detecting element of the sixth embodiment.

Fig. 17 is a graph showing an RH curve of the magnetic element according to the sixth embodiment.

Fig. 18 is a block diagram of a transceiver device of the first application example.

Fig. 19 is a conceptual diagram of an example of a communication system.

Fig. 20 is a conceptual diagram of a cross section of a photosensor device of a second application example.

Fig. 21 is a schematic diagram of an example of a terminal device.

Description of symbols

1. 1' a first ferromagnetic layer, 2' a second ferromagnetic layer, 3' a spacer layer, 4 a buffer layer, 5 a seed layer, 6 a ferromagnetic layer, 7 a magnetic coupling layer, 8 a perpendicular magnetization inducing layer, 9 a cap layer, 10A, 10B, 10C, 10D, 10E, 10F a photodetector element, 11B, 11D, 11F a magnetic element, 12 a first electrode, 13 a second electrode, 20A light irradiation section, 30A magnetic field applying section, 31 a first hard magnetic layer, 32 a second hard magnetic layer, 33 a first light shielding layer, 34 a second light shielding layer, 40 an antiferromagnetic layer, 50A piezoelectric element, 51 a piezoelectric body, 52, 53 an electrode, 90 an insulating layer, 100 an optical device, 120A circuit substrate, 121 analog-digital converter, 122 output terminal, 130 wiring layer, 131 wiring, 132 interlayer insulating film, 300 receiving device, 301 light detecting element, 302 signal processing section, 400 transmitting device, 401 light source, 402 electric signal generating element, 403 light modulating element, 500, 600 terminal device, 1000 transmitting/receiving device, 2000 light sensor device, A1 contains the range of zero external magnetic field intensity, C center, F wavelength filter, F1 tensile stress, F2 compressive stress, L light, L1, L2 light signal, M1, M2, M1', M2', M6, M31, M32 magnetization, R lens, S light sensor, S1 first face, S2 second face.

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings as appropriate. In the drawings used in the following description, features may be enlarged and shown for convenience, and the dimensional proportions of the components may be different from the actual ones. The materials, dimensions, and the like exemplified in the following description are only examples, and the present invention is not limited thereto, and can be implemented with appropriate modifications within the scope of achieving the effects of the present invention.

The direction is defined. One direction of the in-plane direction in which the first ferromagnetic layer 1 of the magnetic element 11 expands is referred to as the x-direction, and the direction orthogonal to the x-direction in-plane is referred to as the y-direction. The plane perpendicular direction perpendicular to the plane (xy plane) in which the first ferromagnetic layer 1 extends is referred to as the z direction. The z-direction is orthogonal to the x-direction and the y-direction. Hereinafter, the +z direction is sometimes referred to as "up", and the-z direction is sometimes referred to as "down". The +z direction is a direction from the second electrode 13 toward the first electrode 12. The up and down direction does not have to coincide with the direction of gravity.

First embodiment

Fig. 1 is a perspective view of an optical device 100 of a first embodiment. The optical device 100 includes, for example, a light detecting element 10 and a light irradiation section 20. The optical device 100 converts the state or the change in state of the light L irradiated from the light irradiation section 20 into an electrical signal by the light detection element 10.

The light irradiation section 20 irradiates the magnetic element 11 with light L. The light irradiation section 20 has, for example, at least one of a light source and an optical member. The light source is, for example, a laser diode, an LED, or the like. The optical component is, for example, a lens, a superlens (Metalens), a wavelength filter, a waveguide, an optical fiber, a reflector, or the like. For example, light L emitted from a light source and passing through or reflected by an optical member is irradiated to the magnetic element 11. The light irradiation unit 20 may have an optical member and no light source, and the light from the outside of the optical device 100 may pass through the optical member as described above as the light irradiation unit 20 or may be reflected by the optical member and then be irradiated to the magnetic element 11. The light irradiation unit 20 may have a light source and no optical member, and the light emitted from the light source included in the light irradiation unit 20 may be irradiated to the magnetic element 11 without passing through the optical member. The light L is, for example, monochromatic light of a single wavelength such as laser light. The light L may be light having a wavelength limited to a range having a certain width, or light having a continuous spectrum, instead of monochromatic light.

The light L is not limited to visible light, and includes infrared rays having a longer wavelength than visible light and ultraviolet rays having a shorter wavelength than visible light. The wavelength of the visible light is, for example, 380nm or more and less than 800nm. The wavelength of infrared light is, for example, 800nm to 1 mm. The wavelength of ultraviolet light is, for example, 200nm or more and less than 380nm. The light L is, for example, light having a high-frequency optical signal and varying in intensity or light having a controlled wavelength band (for example, light passing through a wavelength filter). The high-frequency optical signal is, for example, a signal having a frequency of 100MHz or more.

The light detecting element 10 is formed on a substrate Sub, for example. The light detection element 10 includes, for example, a magnetic element 11, a first electrode 12, a second electrode 13, and a magnetic field applying portion 30.

Fig. 2 is a cross-sectional view of the light detecting element 10 of the first embodiment. In fig. 2, the direction of magnetization of the ferromagnetic body in a state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11 is indicated by an arrow. The first electrode 12 and the second electrode 13 sandwich the magnetic element 11 in the z-direction. The magnetic field applying portion 30 is located at a position where the magnetic element 11 is sandwiched in the x-direction, for example. The periphery of the magnetic element 11 and the magnetic field applying section 30 is covered with an insulating layer 90.

The insulating layer 90 is, for example, an oxide, nitride, oxynitride of Si, al, mg. The insulating layer 90 is, for example, silicon oxide (SiO) _x ) Silicon nitride (SiN) _x ) Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al) ₂ O ₃ ) Zirconium oxide (ZrO) _x ) Etc.

The magnetic element 11 has at least a first ferromagnetic layer 1, a second ferromagnetic layer 2 and a spacer layer 3. The spacer layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. In addition to these, the magnetic element 11 may further include a buffer layer 4, a seed layer 5, a ferromagnetic layer 6, a magnetic coupling layer 7, a perpendicular magnetization inducing layer 8, and a cap layer 9. The buffer layer 4, the seed layer 5, the ferromagnetic layer 6, and the magnetic coupling layer 7 are located between the second ferromagnetic layer 2 and the second electrode 13, and the perpendicular magnetization inducing layer 8 and the capping layer 9 are located between the first ferromagnetic layer 1 and the first electrode 12. For example, the magnetic element 11 has a cylindrical shape, and a planar shape as viewed from the z direction is circular.

The magnetic element 11 is, for example, an MTJ (Magnetic Tunnel Junction (magnetic tunnel junction)) element in which the spacer layer 3 is made of an insulating material. When irradiated with light from the outside, the magnetic element 11 changes its resistance value. The magnetic element 11 changes the resistance value in the z direction (resistance value when a current is caused to flow in the z direction) in response to a relative change in the state of the magnetization M1 of the first ferromagnetic layer 1 and the state of the magnetization M2 of the second ferromagnetic layer 2. Such an element is also called a magnetoresistance effect element.

The first ferromagnetic layer 1 is a light detection layer whose magnetization state changes when irradiated with light L. The first ferromagnetic layer 1 is also referred to as a magnetization free layer. The magnetization free layer is a layer containing a magnetic substance whose magnetization state changes when predetermined energy is applied from the outside. The predetermined energy from the outside is, for example, light irradiated from the outside, current flowing in the lamination direction of the magnetic element 11, and a magnetic field applied from the outside of the first ferromagnetic layer 1. The state of the magnetization M1 of the first ferromagnetic layer 1 varies corresponding to the intensity of the irradiated light L.

The magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to any of the in-plane direction and the in-plane perpendicular direction in a state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11. If the magnetization M1 is inclined with respect to either the in-plane direction or the in-plane perpendicular direction in a state where the light L is not irradiated to the magnetic element 11, the RH curve does not show hysteresis. The RH curve represents the change in resistance of the magnetic element 11 with respect to an external magnetic field applied to the optical device 100. Here, the external magnetic field is a magnetic field applied from outside the optical device 100. The magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to, for example, any direction in the xy plane and the z direction in a state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11.

The first ferromagnetic layer 1 is, for example, a perpendicular magnetization film having an easy axis in the plane perpendicular direction (z direction). By applying a magnetic field having a component in the in-plane direction from the magnetic field applying section 30 described below, the magnetization M1 of the first ferromagnetic layer 1 is tilted from the in-plane perpendicular direction to any one of the in-plane directions (for example, the x-direction). Here, the magnetic field applied to the first ferromagnetic layer 1 from the magnetic field applying section 30 is a magnetic field generated inside the optical device 100, and is not included in an external magnetic field applied from outside the optical device 100, unlike an external magnetic field applied from outside the optical device 100.

The first ferromagnetic layer 1 contains a ferromagnetic body. The first ferromagnetic layer 1 contains at least any one of magnetic elements such as Co, fe, and Ni. The first ferromagnetic layer 1 may contain B, mg, hf, gd and the like together with the above-described magnetic element. The first ferromagnetic layer 1 may be an alloy containing a magnetic element and a non-magnetic element, for example. The first ferromagnetic layer 1 may also be composed of a plurality of layers. The first ferromagnetic layer 1 is, for example, a laminate of CoFeB alloy and CoFeB alloy layers sandwiched between Fe layers, or a laminate of CoFeB alloy layers sandwiched between CoFe layers.

The first ferromagnetic layer 1 may be a laminate in which magnetic layers and nonmagnetic layers are alternately laminated, and may be, for example, a laminate in which Co and Pt are alternately laminated, or a laminate in which Co and Ni are alternately laminated. In general, "ferromagnetic" includes "ferrimagnetism". The first ferromagnetic layer 1 may exhibit ferromagnetism. On the other hand, the first ferromagnetic layer 1 may also exhibit ferromagnetism other than ferrimagnetism. For example, coFeB alloys exhibit ferromagnetism which is not ferrimagnetic.

The film thickness of the first ferromagnetic layer 1 is, for example, 1nm to 5 nm. The film thickness of the first ferromagnetic layer 1 is preferably, for example, 1nm to 2 nm. When the first ferromagnetic layer 1 is a perpendicular magnetization film, if the film thickness of the first ferromagnetic layer 1 is small, the perpendicular magnetic anisotropy application effect from the layers located above and below the first ferromagnetic layer 1 increases, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 increases. That is, when the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is high, the force with which the magnetization is to return to the z direction is enhanced. On the other hand, if the film thickness of the first ferromagnetic layer 1 is large, the perpendicular magnetic anisotropy application effect from the layers located above and below the first ferromagnetic layer 1 is relatively reduced, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is reduced.

When the film thickness of the first ferromagnetic layer 1 becomes thin, the volume as a ferromagnetic body decreases, and when the film thickness becomes thick, the volume as a ferromagnetic body increases. The ease of response of magnetization of the first ferromagnetic layer 1 when external energy is applied is inversely proportional to the product (KuV) of the magnetic anisotropy (Ku) and the volume (V) of the first ferromagnetic layer 1. That is, when the product of the magnetic anisotropy and the volume of the first ferromagnetic layer 1 is reduced, the responsiveness to light is improved. From such a viewpoint, in order to improve the response to light, it is preferable to reduce the volume of the first ferromagnetic layer 1 in addition to properly designing the magnetic anisotropy of the first ferromagnetic layer 1.

When the film thickness of the first ferromagnetic layer 1 is thicker than 2nm, for example, an insertion layer made of Mo or W may be provided in the first ferromagnetic layer 1. That is, a stacked body in which a ferromagnetic layer, an insertion layer, and a ferromagnetic layer are stacked in this order in the z-direction may be used as the first ferromagnetic layer 1. The perpendicular magnetic anisotropy of the first ferromagnetic layer 1 as a whole is improved due to the interfacial magnetic anisotropy at the interface of the insertion layer and the ferromagnetic layer. The thickness of the intercalating layer is, for example, 0.1nm to 0.6nm.

The second ferromagnetic layer 2 is a magnetization pinned layer. The magnetization fixed layer is a layer made of a magnetic material whose magnetization state is less changeable than that of the magnetization free layer when predetermined energy is applied from the outside. For example, when a predetermined energy is applied from the outside to the magnetization fixed layer, the magnetization direction is less likely to change than that of the magnetization free layer. For example, when a predetermined energy is applied from the outside to the magnetization fixed layer, the magnitude of magnetization is less likely to change than that of the magnetization free layer. The coercivity of the second ferromagnetic layer 2 is, for example, greater than the coercivity of the first ferromagnetic layer 1. The second ferromagnetic layer 2 may be an in-plane magnetization film or a perpendicular magnetization film. In the example shown in fig. 2, the direction of magnetization M2 of the second ferromagnetic layer 2 is the z-direction.

The material constituting the second ferromagnetic layer 2 is, for example, the same as that of the first ferromagnetic layer 1. The second ferromagnetic layer 2 may be, for example, a multilayer film in which Co having a thickness of 0.4nm to 1.0nm and Pt having a thickness of 0.4nm to 1.0nm are alternately laminated several times. The second ferromagnetic layer 2 may be a laminate in which Co having a thickness of 0.4nm to 1.0nm, mo having a thickness of 0.1nm to 0.5nm, coFeB alloy having a thickness of 0.3nm to 1.0nm, and Fe having a thickness of 0.3nm to 1.0nm are laminated in this order.

The magnetization M2 of the second ferromagnetic layer 2 can be fixed by, for example, magnetic coupling with the ferromagnetic layer 6 sandwiching the magnetic coupling layer 7. In this case, the component in which the second ferromagnetic layer 2, the magnetic coupling layer 7, and the ferromagnetic layer 6 are bonded together is sometimes referred to as a magnetization pinned layer. Details of the magnetic coupling layer 7 and the ferromagnetic layer 6 are described later.

The spacer layer 3 is a layer disposed between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The spacer layer 3 is constituted by a layer constituted by a conductor, an insulator, or a semiconductor, or by a layer including a conduction point constituted by a conductor in the insulator. The spacer layer 3 is for example a non-magnetic layer. The film thickness of the spacer layer 3 can be adjusted according to the orientation direction of the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2.

For example, in the case where the spacer layer 3 is made of an insulator, the magnetic element 11 has a magnetic tunnel junction (MTJ: magnetic Tunnel Junction) made up of the first ferromagnetic layer 1, the spacer layer 3, and the second ferromagnetic layer 2. Such an element is called an MTJ element. In this case, the magnetic element 11 can exhibit a tunneling magnetoresistance (TMR: tunnel Magnetoresistance) effect. For example, in the case where the spacer layer 3 is composed of metal, the magnetic element 11 can exhibit a giant magnetoresistance (GMR: giant Magnetoresistance) effect. Such an element is called a GMR element. The magnetic element 11 is sometimes called a magnetoresistance effect element, although it is different from an MTJ element, a GMR element, or the like depending on the constituent material of the spacer layer 3.

In the case where the spacer layer 3 is made of an insulating material, a material containing aluminum oxide, magnesium oxide, titanium oxide, silicon oxide, or the like can be used as the material of the spacer layer 3. These insulating materials may contain Al, B, si, mg and other elements, and Co, fe, ni and other magnetic elements. By adjusting the film thickness of the spacer layer 3 so as to exhibit a high TMR effect between the first ferromagnetic layer 1 and the second ferromagnetic layer 2, a high magnetoresistance change rate can be obtained. In order to use the TMR effect efficiently, the thickness of the spacer layer 3 may be about 0.5 to 5.0nm or about 1.0 to 2.5 nm.

In the case where the spacer layer 3 is made of a nonmagnetic conductive material, a conductive material such as Cu, ag, au, or Ru can be used. In order to efficiently use the GMR effect, the thickness of the spacer layer 3 may be about 0.5 to 5.0nm or about 2.0 to 3.0 nm.

In the case where the spacer layer 3 is made of a nonmagnetic semiconductor material, a material such as zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide, or ITO can be used. In this case, the thickness of the spacer layer 3 may be about 1.0 to 4.0 nm.

In the case of applying a layer including a conduction point made of a conductor in a nonmagnetic insulator as the spacer layer 3, such a structure may be adopted: the nonmagnetic insulator made of aluminum oxide or magnesium oxide includes a conduction point made of a nonmagnetic conductor such as Cu, au, or Al. The conductor may be made of a magnetic element such as Co, fe, or Ni. In this case, the thickness of the spacer layer 3 may be about 1.0 to 2.5 nm. The conduction point is, for example, a columnar body having a diameter of 1nm to 5nm when viewed from a direction perpendicular to the film surface.

The ferromagnetic layer 6 is magnetically coupled with the second ferromagnetic layer 2, for example. The magnetic coupling is, for example, an antiferromagnetic coupling, which is produced by RKKY interactions. The direction of the magnetization M2 of the second ferromagnetic layer 2 is in an antiparallel relationship with the direction of the magnetization M6 of the ferromagnetic layer 6. The material constituting the ferromagnetic layer 6 is, for example, the same as the first ferromagnetic layer 1.

The magnetic coupling layer 7 is located between the second ferromagnetic layer 2 and the ferromagnetic layer 6. The magnetic coupling layer 7 is, for example, ru, ir, or the like.

The buffer layer 4 is a layer that alleviates lattice mismatch between different crystals. The buffer layer 4 is, for example, a metal containing at least one element selected from Ta, ti, zr, and Cr, or a nitride containing at least one element selected from Ta, ti, zr, and Cu. More specifically, the buffer layer 4 is, for example, ta (single body), niCr alloy, taN (tantalum nitride), cuN (copper nitride). The film thickness of the buffer layer 4 is, for example, 1nm to 5 nm. The buffer layer 4 is amorphous, for example. The buffer layer 4 is located between the seed layer 5 and the second electrode 13, for example, and contacts the second electrode 13. The buffer layer 4 suppresses the influence of the crystal structure of the second electrode 13 on the crystal structure of the second ferromagnetic layer 2.

The seed layer 5 improves crystallinity of a layer stacked on the seed layer 5. The seed layer 5 is located, for example, between the buffer layer 4 and the ferromagnetic layer 6, and is located on the buffer layer 4. The seed layer 5 is Pt, ru, zr, niFeCr, for example. The thickness of the seed layer 5 is, for example, 1nm to 5 nm.

The capping layer 9 is located between the first ferromagnetic layer 1 and the first electrode 12. The capping layer 9 may include a perpendicular magnetization inducing layer 8 laminated on the first ferromagnetic layer 1 and in contact with the first ferromagnetic layer 1. The cover layer 9 prevents damage to the lower layer during the process and improves crystallinity of the lower layer at the time of annealing. The film thickness of the cover layer 9 is, for example, 10nm or less so that sufficient light is irradiated to the first ferromagnetic layer 1.

The perpendicular magnetization initiation layer 8 initiates perpendicular magnetic anisotropy of the first ferromagnetic layer 1. The perpendicular magnetization initiation layer 8 is, for example, magnesium oxide, W, ta, mo, or the like. In the case where the perpendicular magnetization initiation layer 8 is magnesium oxide, it is preferable that magnesium oxide generates oxygen deficiency in order to improve conductivity. The film thickness of the perpendicular magnetization initiation layer 8 is, for example, 0.5nm to 5.0 nm.

The first electrode 12 is disposed, for example, on the side where light is irradiated to the magnetic element 11. The light L is irradiated from the first electrode 12 side to the magnetic element 11, and at least to the first ferromagnetic layer 1. The first electrode 12 is made of a material having conductivity. The first electrode 12 is, for example, a transparent electrode having transparency to light in the use band. The first electrode 12 preferably transmits, for example, 80% or more of the light in the use wavelength band.

The first electrode 12 is, for example, an oxide such as Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), zinc oxide (ZnO), or Indium Gallium Zinc Oxide (IGZO). The first electrode 12 may have a structure in which a plurality of columnar metals are included in the transparent electrode material of these oxides. The transparent electrode material described above is not necessarily used for the first electrode 12, but a metal material such as Au, cu, or Al may be used in a thin film thickness to allow the irradiated light to reach the first ferromagnetic layer 1. When a metal is used as the material of the first electrode 12, the film thickness of the first electrode 12 is, for example, 3 to 10nm. The first electrode 12 may have an antireflection film on the irradiation surface irradiated with light.

The second electrode 13 is located on the opposite side of the first electrode 12 with the magnetic element 11 interposed therebetween. The second electrode 13 is made of a material having conductivity. The second electrode 13 is made of a metal such as Cu, al, or Au. Ta and Ti may be stacked on top of each other. In addition, a laminated film of Cu and Ta, a laminated film of Ta, cu and Ti, and a laminated film of Ta, cu and TaN may be used. Note that TiN or TaN may be used as the second electrode 13. The film thickness of the second electrode 13 is, for example, 200nm to 800nm.

The second electrode 13 may be transparent to light emitted to the magnetic element 11. As the material of the second electrode 13, for example, a transparent electrode material of an oxide such as Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), zinc oxide (ZnO), or Indium Gallium Zinc Oxide (IGZO) can be used as in the first electrode 12. Even when the light L is irradiated from the first electrode 12 side, there may be a case where the light reaches the second electrode 13 depending on the intensity of the light L, and in this case, the second electrode 13 is formed by a transparent electrode material containing an oxide, and reflection of the light at the interface between the second electrode 13 and the layer in contact therewith can be suppressed as compared with the case where the second electrode 13 is formed of a metal.

The magnetic field applying section 30 applies a magnetic field to the first ferromagnetic layer 1. The magnetic field applying unit 30 is located at a position where light irradiated from the light irradiating unit 20 to the magnetic element 11 is not blocked. The magnetic field applying section 30 is located, for example, at a position not intersecting a line segment connecting the light emitting end of the light irradiation section 20 and the magnetic element 11.

The magnetic field applying section 30 has, for example, a first hard magnetic layer 31 and a second hard magnetic layer 32. The first hard magnetic layer 31 has a first light shielding layer 33 on one surface thereof. The second hard magnetic layer 32 has a second light shielding layer 34 on one side thereof.

The first hard magnetic layer 31 and the second hard magnetic layer 32 are each located at a position overlapping the first ferromagnetic layer 1 when viewed from any direction orthogonal to the z direction. The first hard magnetic layer 31 and the second hard magnetic layer 32 sandwich the first ferromagnetic layer 1 in any one of the in-plane directions (for example, x-direction) via the insulating layer 90, for example.

The first hard magnetic layer 31 and the second hard magnetic layer 32 are hard magnetic bodies. The first hard magnetic layer 31 and the second hard magnetic layer 32 are in-plane magnetization films having an easy axis in the in-plane direction. The magnetization M31 of the first hard magnetic layer 31 and the magnetization M32 of the second hard magnetic layer 32 are oriented in the x direction, for example.

A leakage magnetic field generated between the first hard magnetic layer 31 and the second hard magnetic layer 32 is applied as a bias magnetic field to the first ferromagnetic layer 1. The bias magnetic field acts on the magnetization M1, and the magnetization M1 is inclined with respect to both the in-plane direction and the in-plane perpendicular direction.

The magnetic field applying portion 30 is not irradiated with the light L from the light irradiating portion 20 through the first light shielding layer 33 and the second light shielding layer 34. The first light shielding layer 33 prevents the light L from being irradiated to the first hard magnetic layer 31. The second light shielding layer 34 prevents the light L from being irradiated to the second hard magnetic layer 32. By making the magnetic field applying portion 30 not irradiated with the light L, it is possible to suppress a change in magnetization state of the first hard magnetic layer 31 and the second hard magnetic layer 32 due to a change in state of the light L. The first light shielding layer 33 and the second light shielding layer 34 are, for example, tungsten, tantalum, titanium, or the like.

The first light shielding layer 33 and the second light shielding layer 34 may not be provided in the case where the light L is not irradiated to the magnetic field applying portion 30. For example, when the magnetic field applying portion 30 is sufficiently distant from the magnetic element 11, or when the light L is condensed to the magnetic element 11 by a lens or the like, the light L is not irradiated to the magnetic field applying portion 30.

Next, a mechanism of the operation of the magnetic element 11 will be described. Fig. 3 is a diagram showing a relationship between a change in intensity of light L irradiated to the magnetic element 11 of the first embodiment and a resistance value of the magnetic element 11. The horizontal axis of fig. 3 indicates the intensity of the light L irradiated to the magnetic element 11, and the vertical axis indicates the resistance value of the magnetic element 11.

The output voltage from the magnetic element 11 varies according to the intensity variation of the light L irradiated to the first ferromagnetic layer 1. Contributing to the variation of the output voltage from the magnetic element 11 is the variation of the resistance value of the magnetic element 11 in the lamination direction.

The magnetic element 11 exhibits a first resistance value R1 in a state where the light L from the light irradiation section 20 is not irradiated to the magnetic element 11 (hereinafter referred to as an initial state). The resistance value in the z direction of the magnetic element 11 is obtained by generating a voltage across the z direction of the magnetic element 11 by flowing an induced current in the z direction of the magnetic element 11, and using ohm's law from the voltage value. An output voltage from the magnetic element 11 is generated between the first electrode 12 and the second electrode 13. In the initial state, the output voltage output from the magnetic element 11 assumes a first value.

When the light L is irradiated to the first ferromagnetic layer 1, energy from the outside due to the irradiation of the light L causes the magnetization M1 of the first ferromagnetic layer 1 to tilt from the initial state. In addition, when the intensity of the light L irradiated to the first ferromagnetic layer 1 changes, the degree of inclination of the magnetization M1 of the first ferromagnetic layer 1 changes corresponding to the intensity of the light L. The larger the intensity of the light L irradiated to the first ferromagnetic layer 1, the larger the inclination of the magnetization M1 of the first ferromagnetic layer 1 with respect to the initial state. For example, an angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the initial state and the direction of the magnetization M1 in the state where the light L is irradiated is greater than 0 ° and less than 90 °.

When the magnetization M1 of the first ferromagnetic layer 1 is tilted from the initial state, the resistance value in the z direction of the magnetic element 11 changes from the initial state. For example, the resistance value in the z direction of the magnetic element 11 gradually increases in correspondence with the inclination of the magnetization M1 of the first ferromagnetic layer 1. When the resistance value of the magnetic element 11 in the z direction changes, the output voltage or the output current from the magnetic element 11 changes. For example, the larger the resistance value of the magnetic element 11, the larger the output voltage from the magnetic element 11. In addition, when the magnetic element 11 is connected to a constant voltage source, the larger the resistance value of the magnetic element 11 is, the smaller the output current from the magnetic element 11 is.

When the intensity of the light L irradiated to the magnetic element 11 changes, the output voltage or the output current (the resistance value in the lamination direction of the magnetic element 11) from the magnetic element 11 changes. Therefore, the magnetic element 11 can detect the intensity of the light L as the output voltage or the output current (the resistance value of the magnetic element 11) from the magnetic element 11.

Since the spin transfer torque in the same direction as the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1, the magnetization M1 of the magnetic element 11 returns to the original state when the light L is not irradiated from the light irradiation section 20 to the magnetic element 11. When the magnetization M1 returns to the initial state, the resistance value in the lamination direction of the magnetic element 11 returns to the first resistance value R1, and the output voltage or the output current from the magnetic element 11 returns to the first value.

The output voltage from the magnetic element 11 changes in accordance with the change in the intensity of the light L irradiated to the first ferromagnetic layer 1, and the magnetic element 11 can convert the change in the intensity of the irradiated light L into a change in the output voltage from the magnetic element 11. That is, the magnetic element 11 can convert light into an electrical signal.

Fig. 4 is a graph showing an RH curve (hereinafter, also referred to as "RH curve of the magnetic element 11") of the resistance change of the magnetic element 11 with respect to the external magnetic field applied in the direction of the magnetization M2 (in this example, the z direction) of the second ferromagnetic layer 2 with respect to the optical device 100 of the first embodiment. In the graph shown in fig. 4, the external magnetic field denoted by H is represented as a negative sign of the external magnetic field in the +z direction shown in fig. 2. In a state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction, and thus the RH curve of the magnetic element 11 does not show hysteresis. That is, the state of the magnetization M1 (direction of the magnetization M1) of the first ferromagnetic layer 1 of the magnetic element 11 varies corresponding to the magnitude of the external magnetic field over a range where the magnitude of the external magnetic field is large. The application of the external magnetic field to the optical device 100 is an example of applying energy to the magnetic element 11 from the outside, and the irradiation light L to the magnetic element 11 is also applied with energy from the outside. Therefore, the state of the magnetization M1 (direction of the magnetization M1) of the first ferromagnetic layer 1 of the magnetic element 11 varies corresponding to the variation of the intensity of the light L over a wide intensity range of the light L. Therefore, as shown in fig. 3, the output voltage or output current from the magnetic element 11 (the resistance value of the magnetic element 11) continuously changes corresponding to the change in the intensity of the light L over a wide intensity range of the light L.

Fig. 5 is a graph showing an RH curve of the magnetic element of the comparative example (an RH curve showing a change in resistance of the magnetic element of the comparative example with respect to an external magnetic field in the z direction applied to the optical device of the comparative example). In the graph shown in fig. 5, the external magnetic field denoted by H is represented as a sign of negative in the upper direction (magnetization direction of the magnetization M2') in the schematic diagram of the magnetic element in fig. 5. The magnetic element of the comparative example is the same as the magnetic element 11 of the first embodiment except that the magnetization M1 of the first ferromagnetic layer 1 is oriented in the z direction in a state where the light L is not irradiated to the magnetic element of the comparative example. The magnetic element of the comparative example includes a first ferromagnetic layer 1', a second ferromagnetic layer 2', and a spacer layer 3' sandwiched therebetween. In the magnetic element of the comparative example, the magnetization M1 'of the first ferromagnetic layer 1' is parallel or antiparallel to the magnetization M2 'of the second ferromagnetic layer 2' in a state where the light L is not irradiated to the magnetic element of the comparative example. As shown in fig. 5, the magnetization M1 'of the first ferromagnetic layer 1' and the magnetization M2 'of the second ferromagnetic layer 2' of the magnetic element of the comparative example are in a parallel or antiparallel state and are in a stable state. The RH curve of the magnetic element of the comparative example shows hysteresis in a state where the light L is not irradiated to the magnetic element of the comparative example.

Fig. 6 is a graph showing a relationship between the change in intensity of light L applied to the magnetic element of the comparative example and the resistance value of the magnetic element of the comparative example. The horizontal axis of fig. 6 indicates the intensity of light L irradiated to the magnetic element of the comparative example, and the vertical axis indicates the resistance value of the magnetic element of the comparative example.

The magnetic element of the comparative example exhibits the first resistance value R1' in a state where the light L from the light irradiation section 20 is not irradiated to the magnetic element of the comparative example. In the magnetic element of the comparative example, the magnetization M1 'of the first ferromagnetic layer 1' and the magnetization M2 'of the second ferromagnetic layer 2' are in a stable state in a state in which the light L is not irradiated to the magnetic element of the comparative example. Therefore, when the intensity of the light L irradiated to the first ferromagnetic layer 1' is small and equal to or less than a predetermined threshold value, the magnetization M1' of the first ferromagnetic layer 1' hardly changes. When light L of an intensity exceeding a threshold value is irradiated to the first ferromagnetic layer 1', the magnetization M1' of the first ferromagnetic layer 1' changes. The larger the intensity of the light L irradiated to the first ferromagnetic layer 1', the larger the inclination of the magnetization M1' of the first ferromagnetic layer 1' with respect to the z direction.

Therefore, as shown in fig. 6, when the intensity of the light L is equal to or lower than the threshold value, the resistance value in the z direction of the magnetic element is substantially constant regardless of the intensity of the light L (first resistance value R1'), and when the intensity of the light L exceeds the threshold value, the resistance value changes in accordance with the intensity of the light L. The output voltage or the output current from the magnetic element is substantially constant regardless of the intensity of the light L even when the intensity of the light L is equal to or less than the threshold value, and varies according to the intensity of the light L when the intensity of the light L exceeds the threshold value.

In the photodetector 10, the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11 and the plane perpendicular direction may be, for example, 5 ° or more, or 20 ° or more, or 35 ° or more. Thus, even in a range where the intensity of the light L irradiated to the first ferromagnetic layer 1 is small, the state of the magnetization M1 of the first ferromagnetic layer 1 (the direction of the magnetization M1) changes more reliably in accordance with the intensity change of the light L, and the output voltage or output current from the magnetic element 11 (the resistance value of the magnetic element 11) can be changed continuously in accordance with the intensity change of the light L more reliably. In the photodetector 10, the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11 and the plane perpendicular direction may be, for example, 85 ° or less, 70 ° or less, or 55 ° or less. This can ensure a more reliable movable range of the magnetization M1 with respect to the change in the intensity of the light L, and thus can ensure a more reliable detection range of the intensity of the light L.

The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 and the plane-perpendicular direction in the state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11 (initial state) can be obtained from the relationship between the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 and the direction of the magnetization M2 of the second ferromagnetic layer 2 in the initial state and the direction of the magnetization M2 of the second ferromagnetic layer 2 and the plane-perpendicular direction in the initial state.

The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 and the direction of the magnetization M2 of the second ferromagnetic layer 2 in the initial state is obtained by the following equation (1).

[ 1]

In formula (1), G is satisfied ₀ ＝1/R ₀ 、G _P ＝1/R _min And G _AP ＝1/R _max 。R ₀ 、R _min 、R _max The resistance values of the magnetic element 11 in the state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11 are all the same. R is R ₀ Is the resistance value of the magnetic element 11 in a state where no external magnetic field is applied to the optical device 100. R is R _min The resistance value is a value at which the magnetic element 11 is saturated when the applied intensity of the external magnetic field with respect to the optical device 100 is increased, and the external magnetic field at this time is applied in the direction of the magnetization M2 of the second ferromagnetic layer 2. R is R _max The resistance value is a resistance value at which the magnetic element 11 is saturated when the applied intensity of the external magnetic field with respect to the optical device 100 is increased, and the external magnetic field at this time is applied in the opposite direction to the direction of the magnetization M2 of the second ferromagnetic layer 2.

In the initial state, when the second ferromagnetic layer 2 is a perpendicular magnetization film, the direction of the magnetization M2 of the second ferromagnetic layer 2 is parallel to the plane perpendicular direction, and when the second ferromagnetic layer 2 is an in-plane magnetization film, the direction of the magnetization M2 of the second ferromagnetic layer 2 is perpendicular to the plane perpendicular direction.

As described above, in the optical device 100 of the first embodiment, the output from the magnetic element 11 continuously changes corresponding to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11. Thus, the optical device 100 can detect the intensity of the light L in a wide intensity range of the light L.

The optical device 100 of the first embodiment has been described above by taking a specific example, but the optical device of the first embodiment is not limited to this example.

Fig. 7 is a cross-sectional view of a light detection element 10A of the first modification. In the light detecting element 10A, the first ferromagnetic layer 1 is an in-plane magnetization film, and the first hard magnetic layer 31 and the second hard magnetic layer 32 are perpendicular magnetization films. The magnetization M31 of the first hard magnetic layer 31 and the magnetization M32 of the second hard magnetic layer 32 are oriented, for example, in the z-direction. Other structures of the light detection element 10A of the first modification are the same as those of the light detection element 10.

The leakage magnetic field from the first hard magnetic layer 31 and the leakage magnetic field from the second hard magnetic layer 32 are applied as bias magnetic fields to the first ferromagnetic layer 1. When the first ferromagnetic layer 1 is an in-plane magnetization film, the magnetization M1 is inclined with respect to the in-plane direction and the in-plane perpendicular direction by applying a magnetic field having a component in the in-plane perpendicular direction from the magnetic field applying section 30.

In the photodetector 10A, the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11 and the plane perpendicular direction may be, for example, 5 ° or more, 20 ° or more, or 35 ° or more. In the light detection element 10A in which the first ferromagnetic layer 1 is an in-plane magnetization film, the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the initial state and the plane perpendicular direction may be 0 ° (the direction of the magnetization M1 of the first ferromagnetic layer 1 is parallel to the plane perpendicular direction). That is, in the light detection element 10A in which the first ferromagnetic layer 1 is an in-plane magnetization film, the magnetization M1 of the first ferromagnetic layer 1 may be inclined with respect to the in-plane direction in which the first ferromagnetic layer 1 expands in a state in which light is not irradiated from the light irradiation section 20 to the magnetic element 11. In this case, the RH curve of the magnetic element 11 does not show hysteresis, and the output voltage or the output current (the resistance value of the magnetic element 11) from the magnetic element 11 continuously changes in accordance with the intensity change of the light L over a wide intensity range of the light L. In the photodetector 10A, the angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the initial state and the plane perpendicular direction may be 85 ° or less, or 70 ° or less, or 55 ° or less, for example. This can ensure a more reliable movable range of the magnetization M1 with respect to the change in the intensity of the light L, and thus can ensure a more reliable detection range of the intensity of the light L.

Here, although an example in which the first hard magnetic layer 31 and the second hard magnetic layer 32 are arranged so as to sandwich the first ferromagnetic layer 1 is shown, one hard magnetic layer may be arranged so as to surround the periphery of the first ferromagnetic layer 1.

Second embodiment

The optical device of the second embodiment includes a light detection element 10B and a light irradiation section 20. The structure of the light irradiation section 20 is the same as that of the optical device of the first embodiment. Fig. 8 is a sectional view of a light detecting element 10B of the second embodiment. The light detecting element 10B is different from the light detecting element 10 in that the magnetic field applying portion 30 is not included and the magnetic element 11B includes the antiferromagnetic layer 40. In the light detection element 10B, the same components as those of the light detection element 10 are denoted by the same reference numerals, and description thereof is omitted.

The magnetic element 11B includes an antiferromagnetic layer 40. The antiferromagnetic layer 40 is in contact with the second surface S2 of the first ferromagnetic layer 1 opposite to the first surface S1 in contact with the spacer layer 3.

In the case where the first ferromagnetic layer 1 is a perpendicular magnetization film, microscopic magnetic moments in the antiferromagnetic layer 40 are oriented in the in-plane direction. In the case where the first ferromagnetic layer 1 is a perpendicular magnetization film, the antiferromagnetic layer 40 exerts the same effect as the magnetic field in the in-plane direction applied to the first ferromagnetic layer 1 by exchange bias, and the magnetization M1 is inclined with respect to both the in-plane direction and the perpendicular direction. In the case where the first ferromagnetic layer 1 is an in-plane magnetization film, the microscopic magnetic moment in the antiferromagnetic layer 40 is oriented in the in-plane perpendicular direction. In the case where the first ferromagnetic layer 1 is an in-plane magnetization film, the antiferromagnetic layer 40 exerts the same effect as the effect of applying a magnetic field in the in-plane perpendicular direction to the first ferromagnetic layer 1 by exchange bias, and the magnetization M1 is inclined with respect to both the in-plane direction and the in-plane perpendicular direction. The orientation direction of the microscopic magnetic moment in the antiferromagnetic layer 40 can be freely designed by the direction of the magnetic field when the antiferromagnetic layer 40 is cooled while applying the magnetic field after being heated to the curie temperature or higher.

The antiferromagnetic layer 40 may be a known antiferromagnetic material. The antiferromagnetic layer 40 preferably contains an oxide exhibiting antiferromagnetic properties. If the antiferromagnetic layer 40 is an oxide having permeability to light in the use band, the light L sufficiently reaches the first ferromagnetic layer 1. The antiferromagnetic layer 40 is, for example, nickel oxide (NiO), chromium oxide (Cr ₂ O ₃ ) Cobalt oxide (CoO).

In the light detection element 10B of the second embodiment, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction in a state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11B, and thus the RH curve of the magnetic element 11B does not show hysteresis. Therefore, the optical device of the second embodiment, like the optical device 100 of the first embodiment, continuously changes in response to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11B from the magnetic element 11B.

Third embodiment

The optical device of the third embodiment includes a light detection element 10C and a light irradiation section 20. The structure of the light irradiation section 20 is the same as that of the optical device of the first embodiment. Fig. 9 is a sectional view of a light detecting element 10C of the third embodiment. The light detecting element 10C is different from the light detecting element 10 in that the magnetic field applying section 30 is not included, but the piezoelectric element 50 is included. In the light detection element 10C, the same components as those of the light detection element 10 are denoted by the same reference numerals, and description thereof is omitted.

The light detecting element 10C includes a piezoelectric element 50. The piezoelectric element 50 is located at a position where stress can be applied to the first ferromagnetic layer 1. The piezoelectric element 50 is located, for example, at a position where the light L irradiated from the light irradiation unit 20 to the magnetic element 11 is not blocked. The piezoelectric element 50 is located on the opposite side of the irradiated light with respect to the magnetic element 11, for example. An insulating layer 90 is provided between the piezoelectric element 50 and the magnetic element 11, for example.

The piezoelectric element 50 includes, for example, a piezoelectric body 51 and electrodes 52 and 53. Fig. 9 is a sectional view of the piezoelectric body 51 in a state where no voltage is applied thereto. When a voltage is applied to the piezoelectric body 51 via the electrode 52 and the electrode 53, the piezoelectric body 51 deforms. The piezoelectric element 50 applies stress to the first ferromagnetic layer 1 by deformation of the piezoelectric body 51.

Fig. 10 is a diagram showing a first state of the light detection element 10C of the third embodiment. The left view of fig. 10 is a yz cross-sectional view. The right diagram of fig. 10 is an xy cross-sectional view through the first ferromagnetic layer 1. When a voltage is applied to the piezoelectric body 51, the piezoelectric body 51 deforms. In the first state shown in fig. 10, the piezoelectric body 51 deforms from the state before the voltage is applied so that the center of the piezoelectric body 51 in the x direction is close to the magnetic element 11.

In the first state, a tensile stress F1 in the x-direction is applied to the first ferromagnetic layer 1. When a tensile stress F1 is applied in the x-direction of the first ferromagnetic layer 1, an anisotropic magnetic field is generated due to the magnetostriction effect, and the magnetization M1 of the first ferromagnetic layer 1 is tilted from the z-direction toward the y-direction. As a result, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to both the in-plane direction and the in-plane perpendicular direction. Here, an example in which the tensile stress F1 is applied in the x direction is shown as an example, but the direction in which the tensile stress F1 is applied may be any direction in the in-plane direction. The magnetization M1 of the first ferromagnetic layer 1 is inclined toward an in-plane direction orthogonal to the direction in which the tensile stress F1 acts.

Fig. 11 is a diagram showing a second state of the light detection element 10C of the third embodiment. The left view of fig. 11 is an xz cross-sectional view. The right diagram of fig. 11 is an xy cross-sectional view through the first ferromagnetic layer 1. As shown in fig. 11, when a voltage is applied to the piezoelectric body 51, the piezoelectric body 51 deforms. The second state shown in fig. 11 is a state in which the piezoelectric body 51 is deformed from the state before the voltage is applied so that the center of the piezoelectric body 51 in the x direction is away from the magnetic element 11.

In the second state, compressive stress F2 in the x-direction is applied to the first ferromagnetic layer 1. When compressive stress F2 is applied in the x direction of the first ferromagnetic layer 1, an anisotropic magnetic field is generated due to the magnetostriction effect, and the magnetization M1 of the first ferromagnetic layer 1 is tilted from the z direction toward the x direction. As a result, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to both the in-plane direction and the in-plane perpendicular direction. Here, an example in which the compressive stress F2 is applied in the x direction is shown as an example, but the direction in which the compressive stress F2 is applied may be any direction in the in-plane direction. The magnetization M1 of the first ferromagnetic layer 1 is inclined toward a direction parallel to a direction in which the compressive stress F2 acts.

In the light detection element 10C of the third embodiment, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction in a state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11, and thus the RH curve of the magnetic element 11 does not show hysteresis. Therefore, the optical device of the third embodiment, like the optical device 100 of the first embodiment, continuously changes in response to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11 from the magnetic element 11.

Fourth embodiment

The optical device of the fourth embodiment includes a light detection element 10D and a light irradiation section 20. The structure of the light irradiation section 20 is the same as that of the optical device of the first embodiment. Fig. 12 is a cross-sectional view of a light detecting element 10D of the fourth embodiment. Fig. 13 is a cross-sectional view of a light detecting element 10D of the fourth embodiment. Fig. 12 is an xz section of the light detection element 10D, and fig. 13 is an xy section through the first ferromagnetic layer 1 of the light detection element 10D. The light detecting element 10D is different from the light detecting element 10 in that the magnetic field applying portion 30 is not included, and the top view shape of the magnetic element 11D is different from that of the magnetic element 11. In the light detection element 10D, the same components as those of the light detection element 10 are denoted by the same reference numerals, and description thereof is omitted.

The first ferromagnetic layer 1 of the magnetic element 11D has an elliptical shape in plan view as viewed from the z-direction. The aspect ratio obtained by dividing the length of the first ferromagnetic layer 1 in the long side direction by the length in the short side direction is larger than 1 when viewed from the z direction. In the first ferromagnetic layer 1, an anisotropic magnetic field is generated due to shape anisotropy of the first ferromagnetic layer 1. The magnetization M1 of the first ferromagnetic layer 1 is inclined from the z direction toward the direction in which the anisotropic magnetic field is applied. Here, the first ferromagnetic layer 1 is illustrated as an elliptical shape in plan view, but the present invention is not limited to this example as long as the lengths in the long-side direction and the short-side direction are different.

In the light detection element 10D according to the fourth embodiment, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction in a state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11D, and thus the RH curve of the magnetic element 11D does not show hysteresis. Therefore, the optical device according to the fourth embodiment, like the optical device 100 according to the first embodiment, continuously changes in response to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11D from the magnetic element 11D.

Fifth embodiment

The optical device of the fifth embodiment includes a light detecting element 10E and a light irradiation section 20. The structure of the light irradiation section 20 is the same as that of the optical device of the first embodiment. Fig. 14 is a sectional view of a light detecting element 10E of the fifth embodiment. The light detecting element 10E is different from the light detecting element 10 in that the magnetic field applying section 30 is not included. In the light detection element 10E, the same components as those of the light detection element 10 are denoted by the same reference numerals, and description thereof is omitted.

The magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction in a state where the light L from the light irradiation section 20 is not irradiated to the magnetic element 11. The orientation direction of the magnetization M1 of the first ferromagnetic layer 1 in a state where the light L from the light irradiation section 20 is not irradiated to the magnetic element 11 can be controlled by the thickness of the first ferromagnetic layer 1. If the thickness of the first ferromagnetic layer 1 is small, a perpendicular magnetic anisotropy application effect is strongly generated in the first ferromagnetic layer 1 by its interface with the upper and lower layers, and the magnetization M1 of the first ferromagnetic layer 1 is oriented in the z direction. On the other hand, when the thickness of the first ferromagnetic layer 1 increases, the perpendicular magnetic anisotropy application effect becomes weak, and the magnetization M1 is tilted from the z direction to any one of the in-plane directions.

In the photodetector 10E of the fifth embodiment, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the plane perpendicular direction in a state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11, and thus the RH curve of the magnetic element 11 does not show hysteresis. Therefore, the optical device of the fifth embodiment, like the optical device 100 of the first embodiment, continuously changes in response to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11 from the magnetic element 11.

Sixth embodiment

The optical device of the sixth embodiment includes a light detecting element 10F and a light irradiation section 20. The structure of the light irradiation section 20 is the same as that of the optical device of the first embodiment. Fig. 15 is a cross-sectional view of a light detecting element 10F of the sixth embodiment. Fig. 16 is a sectional view of a light detecting element 10F of the sixth embodiment. Fig. 15 is an xz section of the light detection element 10F, and fig. 16 is an xy section through the first ferromagnetic layer 1 of the light detection element 10F. The light detecting element 10F is different from the light detecting element 10 in that the magnetic field applying portion 30 is not included and the magnetic element 11F is provided instead of the magnetic element 11. In the light detection element 10F, the same components as those of the light detection element 10 are denoted by the same reference numerals, and description thereof is omitted.

The first ferromagnetic layer 1, the second ferromagnetic layer 2, and the ferromagnetic layer 6 of the magnetic element 11F are in-plane magnetization films. The magnetic domain structure of the first ferromagnetic layer 1 of the magnetic element 11F has a vortex (vortex) structure in a state in which the light L is not irradiated from the light irradiation section 20 to the magnetic element 11F. The swirling structure is a structure in which the magnetic moment MM1 swirls in the in-plane direction so as to surround the center C. The swirling structure can be exhibited by adjusting the thickness of the first ferromagnetic layer 1 and the diameter in a plan view. For example, when the first ferromagnetic layer 1 is FeB, the magnetic domain structure of the first ferromagnetic layer 1 becomes a vortex structure when the thickness of the first ferromagnetic layer 1 is 10nm and the diameter is 1.1 μm. For another example, when the first ferromagnetic layer 1 is NiFe, the magnetic domain structure of the first ferromagnetic layer 1 becomes a vortex structure when the thickness of the first ferromagnetic layer 1 is 15nm and the diameter is 170 nm. For another example, when the first ferromagnetic layer 1 is CoFeB, the magnetic domain structure of the first ferromagnetic layer 1 becomes a vortex structure when the thickness of the first ferromagnetic layer 1 is 10nm and the diameter thereof is 300 nm.

Fig. 17 is a graph showing an RH curve of the magnetic element 11F according to the sixth embodiment. In this example, the external magnetic field is a magnetic field in the in-plane direction (x direction in this example) which is the direction of magnetization M2 of the second ferromagnetic layer 2. In the case where the magnetic domain structure of the first ferromagnetic layer 1 is a vortex structure, the RH curve of the magnetic element 11F does not exhibit hysteresis in the range A1 including the external magnetic field intensity of zero in the state where the light L is not irradiated from the light irradiation section 20 to the magnetic element 11F.

In the light detection element 10F according to the sixth embodiment, the RH curve of the magnetic element 11F does not exhibit hysteresis in the range A1 including the external magnetic field intensity of zero in the state where the light L is not irradiated from the light irradiation unit 20 to the magnetic element 11F. Therefore, the optical device according to the sixth embodiment, like the optical device 100 according to the first embodiment, continuously changes in response to the change in the intensity of the light L over a wide intensity range of the light L irradiated to the magnetic element 11F from the magnetic element 11F.

The present invention is not limited to the above-described embodiments and modifications, and various modifications and changes can be made within the scope of the present invention as set forth in the claims. For example, the characteristic structures of the above-described embodiment and modification may be combined.

In addition, the following examples are shown: in the first to fifth embodiments, the magnetization M1 of the first ferromagnetic layer 1 is inclined with respect to the in-plane direction and the in-plane perpendicular direction in a state where the light L is not irradiated to the magnetic element, and in the sixth embodiment, the domain structure of the first ferromagnetic layer 1 is formed into a vortex structure in a state where the light L is not irradiated to the magnetic element, so that a state where the RH curve of the magnetic element does not exhibit hysteresis is realized at least in a range including the external magnetic field intensity of zero. The method of realizing a state in which the RH curve of the magnetic element does not show hysteresis in at least a range including the external magnetic field strength of zero in a state in which the light L is not irradiated to the magnetic element is not limited thereto. As long as the RH profile of the magnetic element does not show hysteresis at least in the range of the external magnetic field intensity including zero in the state where the light L is not irradiated to the magnetic element, the output from the magnetic element can be continuously changed corresponding to the change in intensity of the light throughout a wide intensity range of the light irradiated to the magnetic element.

The optical device according to the above embodiment and modification can be applied to an optical sensor device such as an image sensor, a transceiver device of a communication system, and the like.

Fig. 18 is a block diagram of a transceiver 1000 of the first application example. The transceiver 1000 includes a receiving apparatus 300 and a transmitting apparatus 400. The receiving apparatus 300 receives the optical signal L1, and the transmitting apparatus 400 transmits the optical signal L2.

The receiving device 300 includes, for example, a light detecting element 301 and a signal processing section 302. The component including the photodetector 301 and the light irradiation section that irradiates the light signal L1 can be any of the optical devices of the above embodiments or modifications. In the receiving device 300, light having a high-frequency optical signal L1 and varying intensity is irradiated to the first ferromagnetic layer 1 of the magnetic element, for example, through a lens (not shown) serving as a light irradiation unit. The light detection element 301 converts the light signal L1 into an electrical signal. The signal processing section 302 processes the electric signal converted by the light detection element 301. The signal processing unit 302 receives a signal included in the optical signal L1 by processing an electrical signal generated from the optical detection element 301. The receiving device 300 receives a signal included in the optical signal L1 based on, for example, an output voltage of the magnetic element.

The transmitting device 400 includes, for example, a light source 401, an electric signal generating element 402, and an optical modulation element 403. The light source 401 is, for example, a laser element. The light source 401 may also be located outside the transmitting device 400. The electrical signal generating element 402 generates an electrical signal based on the transmission information. The electric signal generating element 402 may be integrated with the signal converting element of the signal processing unit 302. The optical modulation element 403 modulates light output from the light source 401 based on the electric signal generated by the electric signal generation element 402, and outputs an optical signal L2.

Fig. 19 is a conceptual diagram of an example of a communication system. The communication system shown in fig. 19 has 2 terminal apparatuses 500. The terminal device 500 is, for example, a smart phone, a tablet computer, a personal computer, or the like.

The terminal apparatus 500 includes a receiving apparatus 300 and a transmitting apparatus 400, respectively. The optical signal transmitted from the transmitting apparatus 400 of one terminal apparatus 500 is received by the receiving apparatus 300 of the other terminal apparatus 500. The light used for transmitting and receiving signals between the terminal apparatuses 500 is, for example, visible light. The receiving device 300 has the above-described light detecting element as the light detecting element 301.

Fig. 20 is a conceptual diagram of a cross section of a photosensor device 2000 of a second application example. The photosensor device 2000 includes, for example, a circuit board 120, a wiring layer 130, and a plurality of photosensors S. The wiring layer 130 and the plurality of photosensors S are formed on the circuit substrate 120, respectively.

The plurality of photosensors S each have, for example, a photodetector 10, a wavelength filter F, and a lens R. Although fig. 20 shows an example in which the light detecting element 10 is used, the light detecting element of other embodiments and modifications may be used. In this example, the wavelength filter F and the lens R constitute a light irradiation section. The light passing through the lens R and the wavelength filter F is irradiated to the magnetic element of the light detection element 10.

The wavelength filter F selects light of a specific wavelength and transmits light of a specific wavelength band. The wavelength bands of light transmitted by the respective wavelength filters F may be the same or different. For example, the light sensor device 2000 may include: a photosensor S (hereinafter referred to as a blue sensor) having a wavelength filter F that transmits blue (a wavelength band of 380nm or more and less than 490 nm); a photosensor S (hereinafter referred to as a green sensor) having a wavelength filter F that transmits green (a wavelength band of 490nm or more and less than 590 nm); and a photosensor S (hereinafter referred to as a red sensor) having a wavelength filter F that transmits red light (a wavelength band of 590nm or more and less than 800 nm). The photosensor device 2000 can be used as an image sensor by setting a blue sensor, a green sensor, and a red sensor to 1 pixel and arranging the pixels. In the optical sensor device 2000 shown in fig. 20, the output from the magnetic element 11 of the light detection element 10 is continuously changed over a wide intensity range of light irradiated to the magnetic element 11, corresponding to the change in intensity of light, and therefore the intensity of light can be detected over a wide intensity range.

The lens R condenses the light toward the magnetic element of the light detection element 10. One or a plurality of magnetic elements may be disposed below one wavelength filter F.

The circuit board 120 has, for example, an analog-digital converter 121 and an output terminal 122. The electric signal transmitted from the light sensor S is converted into digital data by the analog-digital converter 121, and is output from the output terminal 122.

The wiring layer 130 has a plurality of wirings 131. An interlayer insulating film 132 is provided between the plurality of wirings 131. The wiring 131 electrically connects each of the photosensors S and the circuit board 120 and each of the arithmetic circuits formed on the circuit board 120. Each of the photosensors S is connected to the circuit board 120 via, for example, a through-line penetrating the interlayer insulating film 132 in the z-direction. By shortening the inter-wiring distance between each of the photosensors S and the circuit substrate 120, noise can be reduced.

The wiring 131 has conductivity. The wiring 131 is, for example, al, cu, or the like. The interlayer insulating film 132 is an insulator that insulates between wirings and between elements of the multilayer wiring. The interlayer insulating film 132 is, for example, an oxide, nitride, or oxynitride of Si, al, or Mg. The interlayer insulating film 132 is, for example, silicon oxide (SiO) _x ) Silicon nitride (SiN) _x ) Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al) ₂ O ₃ ) Zirconium oxide (ZrO) _x ) Etc.

The optical sensor device 2000 described above can be used for a terminal device, for example. Fig. 21 is a schematic diagram of an example of the terminal apparatus 600. The left side of fig. 21 is the surface of the terminal device 600, and the right side of fig. 21 is the back surface of the terminal device 600. The terminal apparatus 600 has a camera CA. The optical sensor device 2000 described above can be used for an image pickup element of the camera CA. In fig. 21, a smart phone is illustrated as an example of the terminal apparatus 600, but the present invention is not limited to this case. The terminal device 600 is, for example, a tablet computer, a personal computer, a digital camera, or the like, in addition to a smart phone.

The present invention is not limited to the above-described embodiments and modifications, and various modifications and changes can be made within the scope of the present invention as set forth in the claims.

Claims

1. An optical device, wherein,

comprises a magnetic element and a light irradiation part,

the light irradiation section irradiates light to the magnetic element,

the magnetic element includes a first ferromagnetic layer irradiated with light, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer,

The magnetization of the first ferromagnetic layer is inclined with respect to both an in-plane direction in which the first ferromagnetic layer expands and a plane perpendicular direction orthogonal to a plane in which the first ferromagnetic layer expands in a state in which light is not irradiated from the light irradiation section to the magnetic element.

2. The optical device of claim 1, wherein,

also comprises a magnetic field applying part which is used for applying the magnetic field,

the magnetic field applying section applies a magnetic field to the first ferromagnetic layer,

the magnetic field applying section is located at a position where light irradiated from the light irradiating section to the magnetic element is not blocked.

3. The optical device of claim 2, wherein,

the light from the light irradiation section is not irradiated to the magnetic field application section.

4. The optical device according to claim 1 to 3, wherein,

the magnetic element further comprises an antiferromagnetic layer,

the antiferromagnetic layer is in contact with a second face of the first ferromagnetic layer opposite the first face in contact with the spacer layer.

5. The optical device of claim 4, wherein,

the antiferromagnetic layer includes an oxide.

6. The optical device of claim 1, wherein,

also included is a piezoelectric element that is configured to be coupled to the piezoelectric element,

the piezoelectric element applies stress to the first ferromagnetic layer.

7. The optical device of claim 6, wherein,

the piezoelectric element is located at a position where light irradiated from the light irradiation unit to the magnetic element is not blocked.

8. The optical device of claim 1, wherein,

the first ferromagnetic layer has an aspect ratio of greater than 1, as viewed from the plane perpendicular direction, obtained by dividing the length in the long side direction by the length in the short side direction.

9. An optical device, wherein,

comprises a magnetic element and a light irradiation part,

the light irradiation section irradiates light to the magnetic element,

an RH curve indicating a change in resistance of the magnetic element with respect to an external magnetic field applied to the optical device does not show hysteresis at least in a range including zero external magnetic field intensity in a state where light is not irradiated from the light irradiation section to the magnetic element.

10. An optical device, wherein,

comprises a magnetic element and a light irradiation part,

the light irradiation section irradiates light to the magnetic element,

The magnetic domain structure of the first ferromagnetic layer has a vortex structure in a state in which light is not irradiated from the light irradiation section to the magnetic element.