Real-space vortex glass imaging and the vortex phase diagram of SnMo6S8

TL;DR

This study uses scanning tunnelling microscopy to image vortices in SnMo6S8, revealing vortex glass behavior and providing insights into vortex phase transitions and disorder at various magnetic fields and temperatures.

Contribution

First large-scale imaging of vortex glass in SnMo6S8, linking vortex disorder with phase transitions and melting behavior.

Findings

Vortex glass observed at 5 and 9T fields.

Magnetisation peak effect coincides with lambda anomaly.

Vortex topological disorder persists below peak effect.

Abstract

Using scanning tunnelling microscopy at 400mK, we have obtained maps of around 100 vortices in SnMo6S8 from 2 - 9T. The orientational and positional disorder at 5 and 9T show that these are the first large-scale images of a vortex glass. At higher temperature a magnetisation peak effect is observed, whose upper boundary coincides with a lambda anomaly in the specific heat. Our data favour a kinetic glass description of the vortex melting transition, indicating that vortex topological disorder persists at fields and temperatures far below the peak effect in low-Tc superconductors.