Flux-pinning mediated superconducting diode effect in the NbSe$_2$/CrGeTe$_3$ heterostructure

TL;DR

This study demonstrates a superconducting diode effect in NbSe$_2$/CrGeTe$_3$ heterostructures, where magnetic domain-controlled flux pinning influences vortex dynamics and critical currents, offering a new way to modulate superconducting diode efficiency.

Contribution

It reveals how flux pinning and magnetic domains in a van der Waals heterostructure can control vortex behavior and diode effects, introducing a novel mechanism for superconducting diode modulation.

Findings

Superconducting diode effect observed in NbSe$_2$/CrGeTe$_3$ heterostructures.

Flux pinning and magnetic domains modulate critical currents.

Critical current depends on magnetic field history.

Abstract

In ferromagnet/superconductor bilayer systems, dipolar fields from the ferromagnet can create asymmetric energy barriers for the formation and dynamics of vortices through flux pinning. Conversely, the flux emanating from vortices can pin the domain walls of the ferromagnet, thereby creating asymmetric critical currents. Here, we report the observation of a superconducting diode effect in a NbSe$_2$/CrGeTe$_3$ van der Waals heterostructure in which the magnetic domains of CrGeTe$_3$ control the Abrikosov vortex dynamics in NbSe$_2$. In addition to extrinsic vortex pinning mechanisms at the edges of NbSe$_2$, flux-pinning-induced bulk pinning of vortices can alter the critical current. This asymmetry can thus be explained by considering the combined effect of this bulk pinning mechanism along with the vortex tilting induced by the Lorentz force from the transport current in the NbSe$_2$/CrGeTe$_3$ heterostructure. We also provide evidence of critical current modulation by flux pinning depending on the history of the field setting procedure. Our results suggest a method of controlling the efficiency of the superconducting diode effect in magnetically coupled van der Waals superconductors, where dipolar fields generated by the magnetic layer can be used to modulate the dynamics of the superconducting vortices in the superconductors.