Calculating the spin memory loss at Cu|metal interfaces from first principles
Ruixi Liu, Kriti Gupta, Zhe Yuan, Paul J. Kelly
Abstract
The role played by interfaces in metallic multilayers is not only to change the momenta of incident electrons; their symmetry lowering also results in an enhancement of the effects of spin-orbit coupling, in particular, the flipping of the spins of conduction electrons. This leads to a significant reduction of a spin current through a metallic interface that is quantitatively characterized by a dimensionless parameter $\ensuremath{\delta}$ called the spin memory loss (SML) parameter, the interface counterpart of the spin-flip diffusion length for bulk metals. In this paper, we use first-principles scattering calculations that include temperature-induced lattice and spin disorder to systematically study three parameters that govern spin transport through metallic interfaces of Cu with Pt, Pd, Py (permalloy), and Co: the interface resistance, spin polarization, and the SML. The value of $\ensuremath{\delta}$ for a $\mathrm{Cu}|\mathrm{Pt}$ interface is found to be comparable to what we recently reported for a $\mathrm{Au}|\mathrm{Pt}$ interface [Gupta et al., Phys. Rev. Lett. 124, 087702 (2020)]. For $\mathrm{Cu}|\mathrm{Py}$ and $\mathrm{Cu}|\mathrm{Co}$ interfaces, $\ensuremath{\delta}$ decreases monotonically with increasing temperature to become negligibly small at room temperature. The calculated results are in good agreement with currently available experimental values in the literature. Inserting a Cu layer between Pt and the Py or Co layers slightly increases the total spin current dissipation at these compound interfaces.