First-principles calculation of the instability leading to giant inverse magnetocaloric effects
D. Comtesse, M. E. Gruner, M. Ogura, V. V. Sokolovskiy, V. D. Buchelnikov, A. Grünebohm, R. Arróyave, N. Singh, T. Gottschall, O. Gutfleisch, V. A. Chernenko, F. Albertini, S. Fähler, P. Entel.
Physical Review B - Condensed Matter and Materials Physics, 89, 184403, (2014)
The structural and magnetic properties of functional Ni-Mn-Z (Z=Ga, In, Sn) Heusler alloys are studied by first-principles and Monte Carlo methods. The ab initio calculations give a basic understanding of the underlying physics which is associated with the strong competition of ferro- and antiferromagnetic interactions with increasing chemical disorder. The resulting d-electron orbital dependent magnetic ordering is the driving mechanism of magnetostructural instability which is accompanied by a drop of magnetization governing the size of the magnetocaloric effect. The thermodynamic properties are calculated by using the ab initio magnetic exchange coupling constants in finite-temperature Monte Carlo simulations, which are used to accurately reproduce the experimental entropy and adiabatic temperature changes across the magnetostructural transition.