Magnetic sensor, magnetic head, and magnetic memory by using spin Hall devices
A magnetic sensor reduces thermal fluctuation and realizes high-sensitive signal detection using a spin Hall device of a simple structure configured with only one magnetic layer. The magnetic sensor includes a stacked film in which a nonmagnetic spin Hall layer, a nonmagnetic insulator layer, and a magnetic layer are stacked, an electrode nonmagnetic terminal pair connected to a side surface of the nonmagnetic spin Hall layer, and a unit applying a current in a film thickness direction of the stacked film. A thickness of the nonmagnetic spin Hall layer is thinner than twice a spin diffusion length of a material constituting the nonmagnetic spin Hall layer. A magnetization direction of the magnetic layer magnetized by an external magnetic field is detected due to the polarity of a voltage across both ends of the electrode nonmagnetic terminal pair.
1. A magnetic sensor comprising:
a stacked film having a nonmagnetic spin Hall layer, a magnetic layer, and a nonmagnetic insulator layer arranged between the nonmagnetic spin Hall layer and the magnetic layer;
an electrode nonmagnetic terminal pair connected to a side surface of the nonmagnetic spin Hall layer; and
a unit applying a current in a film thickness direction of the stacked film,
wherein the nonmagnetic spin Hall layer is a layer in which up spins and down spins of the spin Hall effect are bent in a reverse direction in a nonmagnetic body due to spin-orbital interaction,
a thickness of the nonmagnetic spin Hall layer is thinner than twice a spin diffusion length of a material constituting the nonmagnetic spin Hall layer, and
a magnetization direction of the magnetic layer magnetized by an external magnetic field is detected due to the polarity of a voltage across both ends of the electrode nonmagnetic terminal pair.
2. The magnetic sensor according to claim 1 , wherein the material constituting the nonmagnetic spin Hall layer is a nonmagnetic body having a larger atomic number than Cu, a compound semiconductor selected from the group of gallium arsenide (GaAs), indium arsenide (InAs), aluminum arsenide (AlAs), indium gallium arsenide (InGaAs), indium gallium nitride-gallium nitride superlattice (InGaN/GaN), mercury telluride (HgTe), mercury selenide (HgSe), hydrogen sulfide (b-HgS), droplet (a-Sn), lead telluride (PbTe), lead selenide (PbSe), and lead sulfide (PbS), or a GaAs-based semiconductor.
3. The magnetic sensor according to claim 2 , wherein a material constituting the nonmagnetic insulator layer is magnesium oxide (MgO).
4. The magnetic sensor according to claim 3 , wherein a material constituting the magnetic layer is an element selected from the group of Co, Ni, Fe, and Mn, or an alloy or compound containing at least one of these elements as a main component.
5. The magnetic sensor according to claim 1 , wherein a direction in which the magnetic layer is magnetized by the external magnetic field is perpendicular to a direction between the electrode nonmagnetic terminals.
6. The magnetic sensor according to claim 1 , wherein the electrode nonmagnetic terminal pair and the nonmagnetic spin Hall layer form a tunnel junction.
7. The magnetic sensor according to claim 1 , wherein a high resistive film is provided between the electrode nonmagnetic terminal pair and the nonmagnetic spin Hall layer.
8. The magnetic sensor according to claim 6 , wherein the high resistive film is AlOx.
9. A magnetic head comprising:
a stacked film having a nonmagnetic spin Hall layer, a magnetic layer, and a nonmagnetic insulator layer arranged between the nonmagnetic spin Hall layer and the magnetic layer;
an electrode nonmagnetic terminal pair connected to a side surface of the nonmagnetic spin Hall layer;
a unit applying a current in a film thickness direction of the stacked film; and
a magnetic shield arranged on both side surfaces of the stacked film,
wherein the nonmagnetic spin Hall layer is a layer in which up spins and down spins of the spin Hall effect are bent in a reverse direction in a nonmagnetic body due to spin-orbital interaction,
a thickness of the nonmagnetic spin Hall layer is thinner than twice a spin diffusion length of a material constituting the nonmagnetic spin Hall layer, and
a direction of an external magnetic field applied to the magnetic layer is detected by detecting a magnetization direction of the magnetic layer due to the polarity of a voltage across both ends of the electrode nonmagnetic terminal pair.
10. The magnetic head according to claim 9 , wherein the electrode nonmagnetic terminal pair and the nonmagnetic spin Hall layer form a tunnel junction.
11. The magnetic head according to claim 9 , wherein a high resistive film is provided between the electrode nonmagnetic terminal pair and the nonmagnetic spin Hall layer.
12. The magnetic head according to claim 11 , wherein the high resistive film is AlOx.
13. A magnetic memory comprising:
a stacked film having a nonmagnetic spin Hall layer, a magnetic layer, and a nonmagnetic insulator layer arranged between the nonmagnetic spin Hall layer and the magnetic layer;
an electrode nonmagnetic terminal pair connected to a side surface of the nonmagnetic spin Hall layer;
a unit applying a current in a film thickness direction of the stacked film; and
a unit applying a current between the electrode nonmagnetic terminal pair,
wherein the nonmagnetic spin Hall layer is a layer in which up spins and down spins of the spin Hall effect are bent in a reverse direction in a nonmagnetic body due to spin-orbital interaction,
a thickness of the nonmagnetic spin Hall layer is thinner than twice a spin diffusion length of a material constituting the nonmagnetic spin Hall layer, and
a magnetization direction of the magnetic layer is reversed due to the polarity of a current applied between the electrode nonmagnetic terminal pair.
14. The magnetic memory according to claim 13 , wherein an alloy of NiFe is used for the magnetic layer.
15. The magnetic memory according to claim 13 , wherein the current is applied in the film thickness direction of the stacked film by the unit applying the current in the film thickness direction of the stacked film, and the magnetization direction of the magnetic layer is detected by detecting polarity of a voltage across both ends of the electrode nonmagnetic terminal pair.