Flow Induced Organization and Memory of a Vortex Lattice

TL;DR

This study investigates how a vortex lattice in 2H-NbSe2 crystals reorganizes under current, revealing a dynamic phase diagram with long-term memory effects and regimes where the critical current can be tuned by the drive.

Contribution

It demonstrates experimentally that vortex lattices can undergo dynamic structural changes with long-term memory, introducing a new regime in the vortex phase diagram.

Findings

Vortex lattice reorganizes under applied current.

Long-term memory effect observed after current is turned off.

Identification of a new dynamic regime affecting critical current.

Abstract

We report on experiments probing the evolution of a vortex state in response to a driving current in 2H-NbSe$_2$ crystals. By following the vortex motion with fast transport measurements we find that the current enables the system to reorganize and access new configurations. During this process the system exhibits a long-term memory: if the current is turned off the vortices freeze in place remembering their prior motion. When the current is restored the motion resumes where it stopped. The experiments provide evidence for a dynamically driven structural change of the vortex lattice and a corresponding dynamic phase diagram that contains a previously unknown regime where the critical current can be either $increased$ or $decreased$ by applying an appropriate driving current.