Spin-orbit torque device and manufacturing method thereof
Disclosed herein is a spin-orbit torque device including a lower ferromagnetic layer, a non-magnetic layer bonded to the lower ferromagnetic layer, and an upper ferromagnetic layer bonded to the non-magnetic layer, wherein a magnetization orientation of the lower ferromagnetic layer is randomly distributed. According to the present disclosure, it is possible to provide a magnetic memory device which cannot be physically duplicated and has reconfigurability using a spin-orbit torque.
1. A spin-orbit torque for a physically unclonable functions (PUF) device, comprising:
a lower ferromagnetic layer;
a non-magnetic layer bonded to the lower ferromagnetic layer; and
an upper ferromagnetic layer bonded to the non-magnetic layer;
wherein the lower ferromagnetic layer has horizontal anisotropy and the upper ferromagnetic layer has anisotropy perpendicular to a plane direction of the upper ferromagnetic layer; and
wherein a ratio of magnetic domains with a magnetization direction of +x and magnetic domains with a magnetization direction of-x formed within the lower ferromagnetic layer is 50:50.
2. The spin-orbit torque device of claim 1 , wherein a switching polarity of the upper ferromagnetic layer is determined according to a random magnetization orientation of the lower ferromagnetic layer.
3. The spin-orbit torque device of claim 2 , wherein each of the upper ferromagnetic layer and the lower ferromagnetic layer includes any one among a CoFeB alloy, a CoFe alloy, and a NiFe alloy.
4. The spin-orbit torque device of claim 3 , wherein the non-magnetic layer includes any one of titanium (Ti) and tantalum (Ta).
5. A spin-orbit torque for a physically unclonable functions (PUF) device, comprising:
an antiferromagnetic layer;
a lower ferromagnetic layer bonded to the antiferromagnetic layer;
a non-magnetic layer bonded to the lower ferromagnetic layer; and
an upper ferromagnetic layer which is bonded to the non-magnetic layer and which has perpendicular anisotropy;
wherein a ratio of magnetic domains with a magnetization direction of +x and magnetic domains with a magnetization direction of-x formed within the lower ferromagnetic layer is 50:50; and
wherein exchange coupling anisotropy is formed between the antiferromagnetic layer and the lower ferromagnetic layer.
6. The spin-orbit torque device of claim 5 , wherein the lower ferromagnetic layer is demagnetized.
7. The spin-orbit torque device of claim 6 , wherein a switching polarity of the upper ferromagnetic layer is determined according to a random magnetization orientation of the lower ferromagnetic layer.
8. The spin-orbit torque device of claim 7 , wherein:
each of the upper ferromagnetic layer and the lower ferromagnetic layer includes any one among a CoFeB alloy, a CoFe alloy, and a NiFe alloy; and
the antiferromagnetic layer includes any one of IrMn and PtMn.
9. A method of manufacturing a spin-orbit torque device, comprising:
preparing the spin-orbit torque device of claim 1 ; and
demagnetizing the lower ferromagnetic layer of the spin-orbit torque.
10. The method of claim 9 , wherein the demagnetizing of the lower ferromagnetic layer includes:
heating the spin-orbit torque device; and
applying a magnetic field to the spin-orbit torque device.
11. The method of claim 10 , wherein the heating of the spin-orbit torque device includes heating the lower ferromagnetic layer at a temperature that is greater than or equal to a Neél temperature of the lower ferromagnetic layer.
12. The method of claim 11 , wherein the applying of the magnetic field includes alternating and applying a magnetic field to the spin-orbit torque device in an orientation opposite to a forward orientation by gradually reducing a magnitude of the magnetic field.