Soft magnetic lithography and giant magnetoresistance in superconducting/ferromagnetic hybrids

Abstract

We demonstrate an approach to create a tunable pinning potential in a superconducting/ferromagnetic (SC/FM) hybrid, allowing the switching of their electronic properties through the application of a small magnetic field. Using direct magneto-optical imaging, macroscopic transport, and magnetic measurements, we show that the alignment of stripe domains in the ferromagnet provides a remarkable directionality for the superconducting vortex motion. An analysis of the anisotropic flux motion demonstrates a substantial critical current anisotropy in the superconductor. The possibility of aligning stable lattices of stripe domains in select directions using in-plane magnetic fields allows the realization of soft magnetic lithography for efficient manipulation of supercurrent flow in SC/FM bilayers. Furthermore, in our samples we observed a pronounced magnetoresistance effect yielding 4 orders of magnitude resistivity change in a few millitesla in-plane field.