Plasticity of Ferromagnets near the Curie Point

TL;DR

This paper explains the increased plasticity in ferromagnets near the Curie point as a result of spin-dependent dislocation detachment influenced by magnetic fluctuations, with applications to nickel and gadolinium.

Contribution

It introduces a model linking magnetization fluctuations to dislocation behavior, explaining anomalous plasticity near the Curie point.

Findings

Plasticity increases near the Curie point due to magnetic fluctuations.

The model describes temperature dependence of critical stress in nickel.

External magnetic fields can suppress plasticity anomalies.

Abstract

We propose an explanation of the anomalous growth of plasticity in ferromagnets near the Curie point. We demonstrate that this effect is caused by spin-dependent detachment of dislocations from obstacles under an influence of the internal magnetic field. Magnetization fluctuations grow in the vicinity of the Curie point, yield an increase of the detachment probability and, hence, an increase of the plasticity. We apply this model for a description of the temperature behaviour of the critical stress in nickel and of the microhardness of gadolinium. An external magnetic field suppresses the magnetization fluctuations and, hence may suppress the above singularities.