부산대학교 도서관

We study the temperature dependence of the critical current density, , of a Nb/PdNi (PdNi = Pd84Ni16) bilayer before and after the application of a magnetic field oriented either out-of-the-plane or in-the-plane of the substrate. Nb and PdNi layers interact through both electromagnetic and proximity coupling. The values of strongly depend on the magnetic history of the samples. Indeed, the values measured when the PdNi is in the out-of-plane remanent state are reduced by a factor of two, in the whole investigated temperature range, compared to the case when the PdNi is in the demagnetized state. This behavior can be accounted for by the out-of-plane magnetocrystalline anisotropy of the PdNi layer producing stray fields which, in turn, can induce a spontaneous vortex phase in the Nb layer. The topology of these vortices is strongly modified by the proximity coupling as confirmed by theoretical calculations. The values are only weakly affected by the in-plane remanence of the PdNi layer. [ABSTRACT FROM AUTHOR]