Atomic Spin-orbit Coupling-induced spin-flip scattering at Ferromagnet/Non-magnetic Metal Interface

Spin conservation at an interface influences several spin transport phenomena such as spin-to-charge conversion and spin-orbit torque. If spin flips at the interface, the spin information may be lost, which is called a spin-memory loss. [1] We claim that large atomic spin-orbit coupling(SOC) and interfacial inversion symmetry breaking(ISB) are important elements of spin-flip scattering in the heterostructure that consists of a nonmagnetic metal with strong SOC and a ferromagnet. To study those effects, we calculate the change of spin information during the reflection/transmission using the tight-binding method. Here, we report two main findings. The first is about the spin-flip resulting from the SOC-induced entanglement of spin and orbital degree of freedom. The other is that the inversion symmetry breaking at an interface, which allows specific inter-orbital hopping [2], generates an additional spin-flip. We argue that these processes contribute to the interfacial spin-memory loss and spin transparency in spintronics devices. [1, 3]

[1] J.-C. Rojas-Sanchez et al., Phys. Rev. Lett. 112, 106602 (2014).
[2] Z. Zhong, A. Toth, and K. Held, Phys. Rev. B 87, 161102(R) (2013).
[3] W. Zhang et al., Nat. Phys. 11, 496 (2015).