Spin-orbit torque structure including topological materials and magnetic memory device including the spin-orbit torque structure
The present disclosure provides a spin-orbit torque structure having a high spin Hall angle and low resistance by including a topological material. In addition, the present disclosure provides a spin-orbit torque structure having a low power consumption density by including a topological material. Also, a magnetic memory device including the spin-orbit torque structure is provided.
1. A spin-orbit torque structure comprising:
an electrode layer including a two-dimensional topological material and configured to generate spin current; and
a free magnetic layer in contact with the electrode layer, the free magnetic layer including a ferromagnetic material, and configured to be magnetically switched by receiving a spin-orbit torque by the spin current,
wherein the two-dimensional topological material comprises a topological insulator (TI),
wherein the ferromagnetic material comprises a stack of two-dimensional layers, and
wherein an interface between the electrode layer and the free magnetic layer is atomically flat.
2. The spin-orbit torque structure of claim 1 , wherein the topological insulator comprises at least one of Bi x Se 1-x Sb y Te 1-y (BSTS), Bi 2 Te 2 Se (BTS), or Bi 2 Se 2 Te (BST).
3. The spin-orbit torque structure of claim 1 , wherein the ferromagnetic material has a perpendicular magnetic anisotropy (PMA).
4. The spin-orbit torque structure of claim 1 , wherein the ferromagnetic material has a Curie temperature in a range of 130 K to 330 K.
5. The spin-orbit torque structure of claim 1 , wherein the ferromagnetic material comprises at least one of Fe 3 GeTe 2 (FGT), CrGeTe (CGT), or CrSiTe (CST).
6. The spin-orbit torque structure of claim 1 , wherein the spin-orbit torque structure has a spin Hall angle (θ SH ) of 0.2 or more.
7. The spin-orbit torque structure of claim 1 , wherein the spin-orbit torque structure has a power density of 20 W/m 3 or less.
8. The spin-orbit torque structure of claim 1 , wherein the spin-orbit torque structure comprises only the two-dimensional topological material and the ferromagnetic material.
9. The spin-orbit torque structure of claim 1 , wherein a critical switching charge current density at which the magnetization switching is performed is 10 7 A/cm 2 or less.
10. The spin-orbit torque structure of claim 1 , wherein the two-dimensional topological material comprises a stack of two-dimensional layers.
11. The spin-orbit torque structure of claim 1 , wherein at least one of the two-dimensional topological material or the ferromagnetic material is a van der Waals (vdW) material.
12. The spin-orbit torque structure of claim 1 , wherein the spin current is generated by a spin Hall effect.
13. The spin-orbit torque structure of claim 1 , further comprising:
a capping layer on the electrode layer.
14. A memory device comprising:
the spin-orbit torque structure according to claim 1 ;
a pinned magnetic layer; and
a tunnel barrier between the free magnetic layer of the spin-orbit torque structure and the pinned magnetic layer,
wherein the memory device is configured to change magnetoresistance according to the magnetization switching of the free magnetic layer.
15. The memory device of claim 14 , wherein the memory device is configured to have conductance across the tunnel barrier when a magnetization direction of the free magnetic layer is parallel to a fixed magnetization direction of the pinned magnetic layer.
16. The memory device of claim 14 , wherein the memory device is configured to have resistance across the tunnel barrier when a magnetization direction of the free magnetic layer is antiparallel to a fixed magnetization direction of the pinned magnetic layer.
17. The memory device of claim 14 , wherein the tunnel barrier comprises an oxide of at least one of magnesium (Mg), titanium (Ti), aluminum (Al), magnesium oxide (MgO), magnesium-zinc (MgZn), and magnesium-boron (MgB), and a nitride of titanium (Ti) or vanadium (V).
18. The memory device of claim 14 , wherein the pinned magnetic layer comprises at least one of Fe, Co, Ni, or an alloy thereof.
19. The memory device of claim 18 , wherein the pinned magnetic layer comprises at least one of NiFe, CoFe, NiFeB, CoFeB, NiFeSiB or CoFeSiB.
20. An electronic apparatus comprising the memory device of claim 14 .