Effects of Density of States Asymmetry on Boundary Resistance of Ferromagnetic-Nonferromagnetic Metal Interface

TL;DR

This paper investigates how the asymmetry in the density of states affects boundary resistance in ferromagnetic-nonferromagnetic metal interfaces, revealing that DOS asymmetry influences potential distribution and resistance measurements.

Contribution

It highlights the importance of DOS asymmetry in boundary resistance and provides explicit results for multilayered spin-valve structures.

Findings

Potential falls off exponentially with spin diffusion length.

Boundary resistance depends on measurement proximity to the interface.

Results are robust against surface resistance and spin-flip effects.

Abstract

Asymmetry of conduction of electrons in the spin majority and minority bands of a ferromagnetic metal is well known to produce spin accumulation at the boundary with a normal metal when a current is injected through the interface. However, little emphasis has been put on the density of states (DOS) asymmetry in diffusive ferromagnetic-nonferromagnetic multilayers. We found that if DOS and conduction asymmetry differ, the electric potential in a ferromagnet falls off to its bulk value exponentially on a scale of the spin diffusion length. Therefore the boundary contribution to resistance dramatically depends on whether the potential difference is measured close to the interface or farther than the spin diffusion length from it. This result is not altered by taking surface resistance or spin-flips on the intermetallic boundary into account. Explicit answers for common multilayered spin-valve structures are given.