Domain - wall - induced magnetoresistance in pseudo spin-valve/superconductor hybrid structures

TL;DR

This study demonstrates how domain walls in a pseudo-spin-valve structure affect superconductivity, revealing peak-like magnetoresistance features linked to domain wall stray fields near the transition temperature.

Contribution

It provides new insights into the influence of domain wall stray fields on superconductivity in hybrid structures, with minimized spin scattering effects by specific layer placement.

Findings

Domain walls cause peak-like magnetoresistance features.

Resistance peaks align with magnetization reversal fields.

DW-induced magnetoresistance increases near the superconducting transition.

Abstract

We have studied the interaction between magnetism and superconductivity in a pseudo-spin-valve structure consisting of a Co/Cu/Py/Nb layer sequence. We are able to control the magnetization reversal process and monitor it by means of the giant magnetoresistance effect during transport measurements. By placing the superconducting Nb-film on the top of the permalloy (Py) electrode instead of putting it in between the two ferromagnets, we minimize the influence of spin scattering or spin accumulation onto the transport properties of Nb. Magnetotransport data reveal clear evidence that the stray fields of domain walls (DWs) in the pseudo-spin-valve influence the emerging superconductivity close to the transition temperature by the occurrence of peak-like features in the magneto-resistance characteristic. Direct comparison with magnetometry data shows that the resistance peaks occur exactly at the magnetization reversal fields of the Co and Py layers, where DWs are generated. For temperatures near the superconducting transition the amplitude of the DW-induced magnetoresistance increases with decreasing temperature, reaching values far beyond the size of the giant magnetoresistive response of our structure in the normal state.