Spin orbit torque magnetic memory device
A magnetic memory device may include tunnel junction unit cells, each including a pinned magnetic layer, an insulating layer, and a free magnetic layer which are sequentially stacked, a conductive line structure configured to supply an in-plane current to the unit cells and to include an antiferromagnetic layer, which is provided adjacent to the free magnetic layer, and a ferromagnetic layer, which is provided adjacent to the antiferromagnetic layer and has an in-plane magnetic anisotropy, and a voltage applying unit configured to independently apply a selection voltage to each of the tunnel junction unit cells. Each of the tunnel junction unit cells may have a magnetization direction that is selectively changed by the in-plane current and the selection voltage.
1. A magnetic memory device, comprising:
tunnel junction unit cells, each including a pinned magnetic layer, an insulating layer, and a free magnetic layer which are sequentially stacked;
a conductive line structure configured to supply an in-plane current and connected to the unit cells, the conductive line structure comprising an antiferromagnetic layer, which is provided adjacent to the free magnetic layer, and a ferromagnetic layer, which is provided adjacent to the antiferromagnetic layer and has an in-plane magnetic anisotropy; and
a voltage applying unit configured to independently apply a selection voltage to each of the tunnel junction unit cells, wherein each of the tunnel junction unit cells has a magnetization direction that is selectively changed by the in-plane current and the selection voltage;
wherein the in-plane current flows through both the antiferromagnetic layer of the conductive line structure and the ferromagnetic layer of conductive line structure;
wherein the antiferromagnetic layer of the conductive line structure and the ferromagnetic layer of conductive line structure are elongated to the conductive line structure; and
wherein the conductive line structure is configured to induce a horizontal exchange bias field in the free magnetic layer, and the in-plane current flowing through the conductive line structure produces a spin-orbit spin torque.
2. The magnetic memory device of claim 1 , wherein the pinned magnetic layer and the free magnetic layer are formed of at least one ferromagnetic materials selected from a group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Tb, Pd, Cu, and W.
3. The magnetic memory device of claim 1 , wherein the insulating layer is formed of a material selected from AlOx, MgO, TaOx, ZrOx, and mixtures thereof.
4. The magnetic memory device of claim 1 , wherein each of the antiferromagnetic and ferromagnetic layers included in the conductive line structure is formed of at least one of metallic materials selected from a group consisting of Co, Fe, Ni, Cu, Ta, Pt, W, Hf, Ir, Rh, Pd, Gd, Bi, Ir, and Mn.
5. The magnetic memory device of claim 1 , wherein the antiferromagnetic layer is formed of a material having a ferrimagnetic property and is provided to be in surface contact with the free magnetic layer.
6. The magnetic memory device of claim 1 , wherein the free magnetic layer has perpendicular magnetic anisotropy (PMA).
7. The magnetic memory device of claim 1 , wherein the antiferromagnetic layer and the ferromagnetic layer are provided to be in surface contact with each other.
8. The magnetic memory device of claim 1 , wherein the ferromagnetic layer is configured to induce a horizontal exchange bias in the antiferromagnetic layer, through a thermal annealing process under a horizontal magnetic field.