Domain Wall Pinning for Enhanced Inverse Spin-Switch Effect in Ferromagnet/Superconductor/Ferromagnet Trilayer

We studied the effect of domain wall pinning on the inverse spin-switch (ISS) behavior in pseudo spin-valve ferromagnet/superconductor/ferromagnet (F/S/F) trilayers. The deposited films were patterned to contain a micron-size triangular notch at their centers for the purpose of domain wall pinning by the notch. The magnetoresistance (MR) and resistance-temperature curves of the notch segment and the side segments next to the notch were simultaneously measured, and then compared against each other to investigate the role of the notch as a domain wall pinning site and then its influence on the ISS effect. In the superconducting transition state, the MR of the notch segment showed less variation in the antiparallel domain state in comparison with the side segments. In addition, the transition temperature difference between the on and off states of the ISS effect was found to be larger in the notch segment, which can be interpreted as enhanced ISS performance. These observations of more stable and the enhanced ISS effect in the notch segment was satisfactorily explained by the domain wall pinning due to the notch in F/S/F trilayers.