Low temperature heat capacity of Fe_{1-x}Ga_{x} alloys with large magneostriction

TL;DR

This study investigates the low temperature heat capacity of Fe-Ga alloys with large magnetostriction, analyzing electronic and phononic contributions, and examining how these properties vary with Ga concentration.

Contribution

It provides experimental data and theoretical analysis linking Ga concentration to changes in Debye temperature and electronic structure in Fe-Ga alloys.

Findings

Debye temperature decreases linearly with Ga content

Electronic specific heat coefficient remains constant despite increased magnetoelastic coupling

Band structure calculations reveal spin state compensation at the Fermi level

Abstract

The low temperature heat capacity C_{p} of Fe_{1-x}Ga_{x} alloys with large magnetostriction has been investigated. The data were analyzed in the standard way using electron ($\gamma T$) and phonon ($\beta T^{3}$) contributions. The Debye temperature $\Theta_{D}$ decreases approximately linearly with increasing Ga concentration, consistent with previous resonant ultrasound measurements and measured phonon dispersion curves. Calculations of $\Theta_{D}$ from lattice dynamical models and from measured elastic constants C_{11}, C_{12} and C_{44} are in agreement with the measured data. The linear coefficient of electronic specific heat $\gamma$ remains relatively constant as the Ga concentration increases, despite the fact that the magnetoelastic coupling increases. Band structure calculations show that this is due to the compensation of majority and minority spin states at the Fermi level.