Tunable phase diagram and vortex pinning in a superconductor-ferromagnet bilayer

TL;DR

This study investigates how the domain pattern in a ferromagnet-superconductor bilayer influences vortex pinning and phase diagram tunability, revealing controllable vortex behavior through domain width adjustments.

Contribution

It demonstrates a reversible method to tune the phase diagram and vortex pinning in a ferromagnet-superconductor bilayer via domain pattern control.

Findings

Domain width can be continuously and reversibly tuned.

Vortex pinning strength depends on domain width, temperature, and magnetic field.

The activation energy for vortex pinning varies systematically with these parameters.

Abstract

We have observed the evolution of phase diagram and vortex pinning using a single ferromagnet/superconductor bilayer of [Co/Pt]8/Nb through a special demagnetization procedure. It induces a continuous and reversible change of the domain width with equal positive/negative domains enabling the observation of the predicted tunable phase diagram. The tunable domain pattern also systematically affects vortex pinning. We have determined the dependence of the activation energy of vortex pinning on domain width, temperature, and magnetic field.