Sudden Magnetization Drops in S/F bilayered Structures

Abstract

We report in plane magnetization measurements on Nb/Co bilayers using a thin superconductor Nb$\sim25$ nm and a thick ferromagnet Co$\sim40-55$ nm where Bloch Domain Walls (BDW) are energetically favorable. Here sharp drops in the magnetization are explained as direct consequence of BDW stray fields that induce vortices in the out of plane direction. These are generated at small fields around the coercive field of the ferromagnet and removed at large fields of the order of $H_{c2}$. These two well distinctive magnetic states of the superconductor, with or without out of plane vortices, is the same mechanism used to explain the drops in critical currents reported in [E. J. Pati$\~{n}$o et. al., The European Physical Journal B 68, 73 (2009)]