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

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 pseudospin valve influence the emerging superconductivity close to the transition temperature by the occurrence of peaklike 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.

Memory effect and triplet pairing generation in the superconducting exchange biased Co/CoOx/Cu41Ni59/Nb/Cu41Ni59 layered heterostructure

“…The kink in the resistance at -4.4 kOe of the BB branch could possibly also be interpreted as the vanishing of a stray field induced increase of R(H) due to an inhomogeneous magnetization indicated by the only nearly flat (inclination increasing in trained state) m(H) range between -1.2 and -4 kOe [17][18][19]37 . Magnetostatic coupling between magnetic microstructures enhances the alignment 38 and intensifies the stray field penetrating the superconductor 19 .…”