Large Asymmetric Spin-Scattering at Ferromagnet/Nonmagnetic Interfaces Predicted from Combined First-Principles Methods

We first reproduced the experimental spin-scattering asymmetry parameter, γ, for Co/Pt and Ni₈₁Fe₁₉/Pt interfaces [1], using a combination of first-principles methods, specifically DFT and asymmetric multichannel Landauer formulations, applied to FM/Pt (FM: Co, Ni) interfaces. Our results reaffirm the relevance of Barnás-Fert’s theory [2], which addresses scattering due to interface potential barriers from shifted electronic bands of the FM layer (relative to Pt), in determining spin-dependent interface resistance and, consequently, γ. With this, we also confirmed the experimental findings on the relationship between γ and the spin polarization of bulk FM. Furthermore, we extended the methods to other elemental FM/NM interfaces (NM: Ru, Rh, Pd, Ag, Os, Ir, Au), and found larger γ values for FM (Fe, Co) interfaces with NM (Ru, Rh, Pd, Ag). Thus, this combined first-principles approach provides a faster and simpler means of predicting the spin-injection parameter at metal interfaces, offering a complementary perspective to its macroscopic evaluation.

[1] V. T. Pham et al., Phys. Rev. Lett. 103 (2021) L201403.

[2] T. Valet and A. Fert, Phys. Rev. B 48 (1993) 7099.