Boundary resistance in magnetic multilayers

TL;DR

This paper derives quasiclassical boundary conditions for electrochemical potentials at ferromagnetic/non-magnetic metal interfaces, enabling better understanding of boundary resistance and spin polarization estimation in magnetic multilayers.

Contribution

It introduces the first derivation of boundary conditions that incorporate momentum conservation and potential gradients, advancing the modeling of magnetic multilayer interfaces.

Findings

Boundary resistance expression accounts for momentum conservation.

Conditions for positive or negative spin asymmetry are established.

Theory consistent with existing experimental data.

Abstract

Quasiclassical boundary conditions for electrochemical potentials at the interface between diffusive ferromagnetic and non-magnetic metals are derived for the first time. An expression for the boundary resistance accurately accounts for the momentum conservation law as well as essential gradients of the chemical potentials. Conditions are established at which spin-asymmetry of the boundary resistance has positive or negative sign. Dependence of the spin asymmetry and the absolute value of the boundary resistance on the exchange splitting of the conduction band opens up new possibility to estimate spin polarization of the conduction band of ferromagnetic metals. Consistency of the theory is checked on existing experimental data.