Multisite Exchange-Enhanced Barocaloric Response in Mn3NiN

Abstract

We study the barocaloric effect (BCE) in the geometrically frustrated antiferromagnet Mn3NiN across the Néel transition temperature. Experimentally, we find a larger barocaloric entropy change by a factor of 1.6 than that recently discovered in the isostructural antiperovskite Mn3GaN despite significantly greater magnetovolume coupling in Mn3GaN. By fitting experimental data to theory, we show that the larger BCE of Mn3NiN originates from multisite exchange interactions amongst the local Mn magnetic moments and their coupling with itinerant electron spins. Using this framework, we discuss the route to maximize the BCE in the wider Mn3AN family.