Negative magnetic relaxation in superconductors

TL;DR

This paper explains the phenomenon of negative magnetic relaxation in high-temperature superconductor tablets and annuli, attributing it to radial temperature gradients during pulsed field magnetization within the Bean critical-state model.

Contribution

It demonstrates that radial temperature gradients can account for negative magnetic relaxation, providing a theoretical explanation within the Bean model.

Findings

Radial temperature gradients occur during pulsed magnetization.

Negative relaxation is explained by temperature-induced changes in the critical current.

The Bean model successfully describes this phenomenon.

Abstract

It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation) if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.