Dynamic ordering of driven vortex matter in the peak effect regime of amorphous MoGe films and 2H-NbSe2 crystals

TL;DR

This study investigates how vortex matter in amorphous MoGe films and 2H-NbSe2 crystals dynamically orders under drive, revealing a divergence in ordering velocity linked to the thermodynamic melting curve, distinct from disorder effects.

Contribution

It demonstrates the divergence of dynamic ordering velocity in vortex matter and links it to the thermodynamic melting curve, providing new insights into vortex phase transitions.

Findings

Divergence of dynamic ordering frequency in the peak effect regime.

Dynamic critical current exhibits a pronounced peak.

Mapping phase diagrams shows divergence aligns with the thermodynamic melting curve.

Abstract

Dynamic ordering of driven vortex matter has been investigated in the peak effect regime of both amorphous MoGe films and 2H-NbSe2 crystals by mode locking (ML) and dc transport measurements. ML features allow us to trace how the shear rigidity of driven vortices evolves with the average velocity. Determining the onset of ML resonance in different magnetic fields and/or temperatures, we find that the dynamic ordering frequency (velocity) exhibits a striking divergence in the higher part of the peak effect regime. Interestingly, this phenomenon is accompanied by a pronounced peak of dynamic critical current. Mapping out field-temperature phase diagrams, we find that divergent points follow well the thermodynamic melting curve of the ideal vortex lattice over wide field and/or temperature ranges. These findings provide a link between the dynamic and static melting phenomena which can be distinguished from the disorder induced peak effect.