Magnetic tunnel junction device with spin-filter structure
A magnetic device includes a conductive layer into which current can be injected in a first direction, the conductive layer causing spin Hall effect or Rashba effect. A ferromagnetic layer is disposed in contact with the conductive layer such that the ferromagnetic layer and the conductive layer are stacked on each other, a magnetization direction of the ferromagnetic layer being switched. A spin filter structure has a fixed magnetization direction, the spin filter structure being disposed on at least one of the opposite side surfaces of the first direction of the conductive layer to inject spin-polarized current into the conductive layer.
1. A magnetic tunnel junction memory device comprising:
a magnetic tunnel junction comprising:
a pinned magnetic layer,
a free magnetic layer, and
a tunnel barrier layer interposed between the pinned magnetic layer and the free magnetic layer;
a conductive pattern to which in-plane direct current is configured to flow, the conductive pattern being disposed in contact with the free magnetic layer of the magnetic tunnel junction to cause spin Hall effect or Rashba effect to apply a spin torque to the free magnetic layer of the magnetic tunnel junction to switch a magnetization direction of the free magnetic layer by the spin torque due to spin Hall effect or Rashba effect; and
a pair of spin filter structures disposed on both side surfaces of the conductive pattern in a direction in which in-plane direct current is applied, wherein the spin filter structures have a fixed magnetization direction,
wherein the spin filter structures are configured to filter injected current to control amount and direction of a spin and to supply filtered current to the conductive pattern,
wherein the magnetization direction of the free magnetic layer is parallel or anti-parallel to a magnetization direction of the pinned magnetic layer,
wherein the fixed magnetization direction of each of the spin filter structures is parallel or anti-parallel to the magnetization direction of the free magnetic layer,
wherein the fixed magnetization direction of the spin filter structures is antiparallel at both sides of the conductive layer, and
wherein the conductive pattern is only formed of non-magnetic metal.
2. The magnetic tunnel junction memory device according to claim 1 , wherein spin polarization of the spin filter structure is greater than 0 and equal to or smaller than 1.
3. The magnetic tunnel junction memory device according to claim 1 , wherein the spin filter structure is a half-metallic ferromagnet.
4. The magnetic tunnel junction memory device according to claim 3 , wherein the half-metallic ferromagnet includes at least one of a Heusler alloy, magnetite (Fe 3 O 4 ), and lanthanum strontium manganite (LSMO).
5. The magnetic tunnel junction device according to claim 1 , wherein
the spin filter structures include a ferromagnet.
6. The magnetic tunnel junction memory device according to claim 1 , wherein the conductive pattern and the free magnetic layer are aligned vertically with each other.
7. The magnetic tunnel junction memory device according to claim 1 , wherein the free magnetic layer has perpendicular magnetic anisotropy (PMA) and the pinned magnetic layer has PMA.
8. The magnetic tunnel junction memory device according to claim 1 , wherein a spin-flip diffusion length of the conductive pattern is between 3 and 4 nanometers.
9. The magnetic tunnel junction memory device according to claim 1 , wherein:
the pinned magnetic layer has a synthetic antiferromagnetic structure including a first pinned magnetic layer, a non-magnetic layer for a pinned magnetic layer, and a second pinned magnetic layer which are sequentially stacked,
each of the first pinned magnetic layer and the second pinned magnetic layer independently includes at least one of Fe, Co, Ni, Gd, B, Si, Zr, and a combination thereof, and
the non-magnetic layer for a pinned magnetic layer includes at least one of Ru, Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.
10. The magnetic tunnel junction memory device according to claim 1 , wherein:
the pinned magnetic layer has an exchange-biased antiferromagnetic structure including an antiferromagnetic layer, a first pinned magnetic layer, a non-magnetic layer, for a pinned magnetic layer, and a second pinned magnetic layer which are sequentially stacked,
the antiferromagnetic layer is formed of one selected from the group consisting of Pt, Ir, Fe, Mn, and a combination thereof,
each of the first pinned magnetic layer and the second pinned magnetic layer independently includes at least one of Fe, Co, Ni, Gd, B, Si, Zr, and a combination thereof, and
the non-magnetic layer for a pinned magnetic layer includes at least one of Ru, Ta, Cu, Pt, Pd, W, Cr, and a combination thereof.
11. The magnetic tunnel junction memory device according to claim 1 , wherein the tunnel barrier layer is formed of one selected from the group consisting of AlO x , MgO, TaO x , ZrO x , and a combination thereof.
12. The magnetic tunnel junction memory device according to claim 1 , wherein:
the conductive pattern provides a spin-orbit torque (SOT) resulting from a spin-orbit coupling force between the free magnetic layer and the conductive pattern, and
the conductive pattern is formed of one selected from the group consisting of Cu, Ta, Pt, W, Bi, Ir, Ti, Pd, Re, Os, Hf, Mo, Ru, and a combination thereof.
13. The magnetic tunnel junction memory device according to claim 1 , wherein the free magnetic layer includes at least one magnetic domain structure.
14. The magnetic tunnel junction memory device according to claim 1 , comprising:
a dipole field non-magnetic layer and a dipole field magnetic layer having an in-plane magnetization direction which are sequentially stacked adjacent to the pinned magnetic layer,
wherein the dipole field non-magnetic layer is disposed adjacent to the pinned magnetic layer, and
wherein the free magnetic layer is configured to be switched without an external magnetic field.