Anomalous behavior of the irreversible magnetization and time relaxation in YBa$_2$Cu$_3$O$_7$ single crystals with splayed tracks

TL;DR

This study investigates the angular dependence of magnetization and its relaxation in YBa₂Cu₃O₇ single crystals with columnar defects, revealing an anomalous behavior at low fields explained by vortex interactions.

Contribution

The paper introduces a model explaining the anomalous magnetization and relaxation behavior based on vortex-vortex interactions and creep process slowdown.

Findings

High-field magnetization peaks at defect orientation

Low-field anomalous minimum in magnetization observed

Model attributes anomalies to vortex interaction effects

Abstract

We have studied the angular dependence of the irreversible magnetization and its time relaxation in YBa$_2$Cu$_3$O$_7$ single crystals with one or two families of columnar defects inclined with respect to the c-axis. At high magnetic fields, the magnetization shows the usual maximum centered at the mean tracks' orientation and an associated minimum in the normalized relaxation rate. In contrast, at low fields we observe an anomalous local minimum in the magnetization and a maximum in the relaxation rate. We present a model to explain this anomaly based on the slowing down of the creep processes arising from the increase of the vortex-vortex interactions as the applied field is tilted away from the mean tracks' direction.