Glassiness in vortex matter in MgB2 probed by a novel scaling method for creep analysis

TL;DR

This study investigates vortex glassiness in MgB2 superconductors using a new scaling method for creep analysis, revealing collective vortex behavior with intermediate creep characteristics.

Contribution

A novel self-consistent scaling method is introduced to analyze vortex creep in MgB2, providing new insights into its glassy vortex dynamics.

Findings

Vortex dynamics in MgB2 exhibit glassy behavior with a critical exponent ~1.

The creep behavior is characterized as collective creep in the intermediate vortex bundle regime.

The new scaling method effectively extracts activation energies from relaxation data.

Abstract

The glassy dynamics is a consequence of the elastic properties of the vortex matter, and in principle may occur in any superconductor. However, whereas a large amount of experimental evidence confirms glassiness in high Tc superconductors (HTS), the applicability of the whole framework developed to describe vortex matter in HTS to other superconducting materials is unclear. In this framework, the particular creep behavior of MgB2, larger than creep of conventional superconductor materials but much lower than HTS one, had precluded a complete understanding of the vortex regimes in this material. In this work we present an experimental study of relaxation processes of pure MgB2 bulk samples measured by DC magnetization technique. We propose a novel self-consistent scaling method to analyze the data and extract the activation energies. The observed experimental behavior can be described in a glassy picture, with a unique critical exponent &mu~1, characteristic of collective creep in the intermediate vortex bundle regime.