Stray field and vortex controlled magnetoresistance in superconducting Bi/Ni bilayers

The magnetoresistance of superconducting Bi/Ni bilayers is investigated around the superconducting transition temperature. At temperatures within the superconducting transition, the magnetoresistance presents a superposition of symmetric peaks and hysteresis behaviors. The magnetoresistance peaks show the evidence of TC suppression due to stray fields from domain walls appearing during magnetization switching. The hysteresis behaviors show the effect of vortices motion on the superconductivity of Bi/Ni bilayers. This unusual magnetoresistance controlled by both stray fields and vortices provides a new understanding of the interaction between superconductivity and ferromagnetism in Bi/Ni bilayers.