Anisotropic Transport Properties of Ferromagnetic-Superconducting Bilayers

TL;DR

This paper investigates the anisotropic transport behavior of vortex matter in ferromagnetic-superconducting bilayers with stripe structures, revealing directional differences in resistance and vortex dynamics.

Contribution

It introduces a detailed analysis of vortex transport in FM-SC bilayers with stripe inhomogeneity, highlighting anisotropic effects and vortex motion characteristics.

Findings

Transport is highly anisotropic in FM-SC bilayers.

Finite resistance occurs perpendicular to stripes without random pinning.

Superconductivity persists parallel to stripes under certain conditions.

Abstract

We study the transport properties of vortex matter in a superconducting thin film separated by a thin insulator layer from a ferromagnetic layer. We assume an alternating stripe structure for both FM and SC layers as found in [7]. We calculate the periodic pinning force in the stripe structure resulting from a highly inhomogeneous distribution of the vortices and antivortices. We show that the transport properties in FM-SC bilayer are highly anisotropic. In the absence of random pinning it displays a finite resistance for the current perpendicular to stripes and is superconducting for the current parallel to stripes. The average vortex velocity, electric field due to the vortex motion, Josephson frequency and higher harmonics of the vortex oscillatory motion are calculated.