Premartensitic transition driven by magnetoelastic interaction in bcc ferromagnetic $Ni_{2}MnGa$

TL;DR

This paper demonstrates that magnetoelastic coupling induces a first-order premartensitic transition in Ni2MnGa, supported by experimental evidence and a predictive model, revealing new insights into phase transitions in ferromagnetic materials.

Contribution

It introduces a model linking magnetoelastic interaction to premartensitic transition, validated by experimental measurements in Ni2MnGa.

Findings

Magnetoelastic coupling enables premartensitic transition.

Experimental evidence from AC susceptibility and ultrasonic measurements.

Measured latent heat matches model predictions.

Abstract

We show that the magnetoelastic coupling between the magnetization and the amplitude of a short wavelength phonon enables the existence of a first order premartensitic transition from a bcc to a micromodulated phase in $Ni_{2}MnGa$. Such a magnetoelastic coupling has been experimentally evidenced by AC susceptibility and ultrasonic measurements under applied magnetic field. A latent heat around 9 J/mol has been measured using a highly sensitive calorimeter. This value is in very good agreement with the value predicted by a proposed model.