Anisotropic magnetic deflagration in single crystals of Gd5Ge4

TL;DR

This study demonstrates the anisotropic nature of magnetic deflagration in Gd5Ge4 single crystals, showing how magnetic field orientation and surface acoustic waves influence the phase transition dynamics.

Contribution

It provides experimental evidence of magnetic deflagration anisotropy and explores the effects of magnetic field, temperature, and surface acoustic waves on the phenomenon.

Findings

Magnetic deflagration is anisotropic and depends on crystallographic direction.

Surface acoustic waves can trigger and influence deflagration fronts.

Thermal diffusivity in Gd5Ge4 is anisotropic, following a>b>c.

Abstract

Experimental evidence of the anisotropy of the magnetic deflagration associated with the low-temperature first order antiferromagnetic (AFM) --> ferromagnetic (FM) phase-transition in single crystals of Gd5Ge4 is reported. The deflagrations have been induced by controlled pulses of surface acoustic waves (SAW) allowing us to explore both the magnetic field and temperature dependencies on the characteristic times of the phenomenon. The study was done using samples with different geometries and configurations between the SAW pulses and the direction of the applied magnetic field with respect to the three main crystallographic directions of the samples. The effect of temperature is nearly negligible, whereas observed strong magnetic field dependence correlates with the magnetic anisotropy of the sample. Finally, the role of the SAW pulses in both the ignition and formation of the deflagration front was also studied, and we show that the thermal diffusivity of Gd5Ge4 must be anisotropic, following \kappaa>\kappab>\kappac.