Magneto-elastic coupling and competing entropy changes in substituted CoMnSi metamagnets

TL;DR

This study investigates the magneto-elastic coupling and entropy changes in CoMnSi-based antiferromagnets, revealing the interplay between electronic and lattice contributions at the metamagnetic transition.

Contribution

It provides detailed insights into the origin of entropy changes, emphasizing the importance of electronic density of states and lattice effects in substituted CoMnSi metamagnets.

Findings

Large difference in electronic density of states between magnetic states

Significant counteracting lattice entropy component

Importance of accurate electronic density of states modeling

Abstract

We use neutron diffraction, magnetometry and low temperature heat capacity to probe giant magneto-elastic coupling in CoMnSi-based antiferromagnets and to establish the origin of the entropy change that occurs at the metamagnetic transition in such compounds. We find a large difference between the electronic density of states of the antiferromagnetic and high magnetisation states. The magnetic field-induced entropy change is composed of this contribution and a significant counteracting lattice component, deduced from the presence of negative magnetostriction. In calculating the electronic entropy change, we note the importance of using an accurate model of the electronic density of states, which here varies rapidly close to the Fermi energy.