Magnetic behavior of superconductor/ferromagnet superlattices

Abstract

A study of the electromagnetic response of superconductor/ferromagnet $\mathrm{Nb}∕\mathrm{Co}$ superlattices is presented. The dc magnetization is measured as a function of Co layer thickness, applied field $H_a$, and temperature. For very thin Co layers, no ferromagnetism is detected and the observed response is essentially that of a collection of uncoupled Nb layers. When the Co layer is thick enough for ferromagnetism to be established, prior to the field-cooled magnetization measurements, the Co layers are magnetically saturated in the parallel or antiparallel directions to $H_a$. In this case, the magnetic response of the otherwise uncoupled Nb layers is found to depend on both $H_a$ and the stray fields.