Suppression of Giant Magnetoresistance by a superconducting contact

TL;DR

This paper predicts that superconducting contacts can significantly suppress giant magnetoresistance in magnetic multilayers due to a superconductivity-induced magneto-resistive effect, confirmed through theoretical calculations.

Contribution

It introduces the superconductivity-induced magneto-resistive (SMR) effect and demonstrates its impact on GMR suppression using ab-initio and simplified models.

Findings

GMR is suppressed when one contact is superconducting.

The suppression persists even with impurity scattering.

The effect is demonstrated in both detailed and simplified models.

Abstract

We predict that current perpendicular to the plane (CPP) giant magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed when one of the contacts is superconducting. This is a consequence of a superconductivity-induced magneto-resistive (SMR) effect, whereby the conductance of the ferromagnetically aligned state is drastically reduced by superconductivity. To demonstrate this effect, we compute the GMR ratio of clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd tight binding Hamiltonian. By analyzing a simpler model with two orbitals per site, we also show that the suppression survives in the presence of elastic scattering by impurities.