Influence of crystal anisotropy on the critical state stability and flux jumps dynamics in a single crystal of La(1.85)Sr(0.15)CuO(4)

TL;DR

This study investigates how crystal anisotropy affects the stability of the critical state and flux jump dynamics in a La(1.85)Sr(0.15)CuO(4) single crystal, revealing the influence of cooling conditions and magnetic diffusivity.

Contribution

It provides experimental validation of models predicting flux jump behavior considering cooling conditions and magnetic diffusivity in high-temperature superconductor crystals.

Findings

Flux jumps occur at lower magnetic diffusivity conditions.

Critical state stability depends on cooling conditions.

First flux jump field decreases with increasing magnetic field sweep rate.

Abstract

We studied the critical state stability in a large cubic sample of a single crystalline La(1.85)Sr(0.15)CuO(4) for different sample orientations with respect to the external magnetic field as well as the dynamics of the flux jumps. It is shown that thermomagnetic avalanches develop in dynamic conditions characterized by significantly lower magnetic diffusivity than the thermal one. In this case, critical state stability depends strongly on cooling conditions. We compared predictions of the isothermal model and of the model for the weakly cooled sample with experimental results. In both models, the field of the first flux jump decreases with an increase of sweep rate of the external magnetic field. We also investigated the influence of external magnetic field on the dynamics of the following stages of the thermomagnetic avalanche. It is shown that the dynamics of the flux jumps is correlated with the magnetic diffusivity proportional to the flux flow resistivity.