Multi-site exchange enhanced barocaloric response in Mn$_{3}$NiN

TL;DR

This study investigates the barocaloric effect in Mn$_{3}$NiN, revealing a significant entropy change driven by multi-site exchange interactions, with implications for enhancing caloric responses in related materials.

Contribution

It demonstrates that multi-site exchange interactions enhance the barocaloric effect in Mn$_{3}$NiN, providing a theoretical framework for optimizing BCE in the Mn$_{3}$AN family.

Findings

Mn$_{3}$NiN exhibits a 1.6 times larger BCE than Mn$_{3}$GaN.

Multi-site exchange interactions are key to the enhanced BCE.

Theoretical modeling links magnetic interactions to caloric response.

Abstract

We have studied the barocaloric effect (BCE) in the geometrically frustrated antiferromagnet Mn$_{3}$NiN across the N\'{e}el transition temperature. Experimentally we find a larger barocaloric entropy change by a factor of 1.6 than that recently discovered in the isostructural antiperovskite Mn$_{3}$GaN despite greater magnetovolume coupling in the latter. By fitting experimental data to theory we show that the larger BCE of Mn$_{3}$NiN originates from multi-site exchange interactions amongst the local Mn magnetic moments and their coupling with itinerant electron spins. Using this framework, we discuss the route to maximise the BCE in the wider Mn$_{3}$AN family.