Thermodynamic analysis of possible phase states in Ni50Mn35In15 Heusler alloy

In this work, a phenomenological Ginzburg-Landau free-energy model is developed for investigating structural and magnetic phase transitions in Heusler alloy Ni50Mn35In15. In particular, our model accounts for the inversion of the exchange interaction, which is coupled to the structural parameters of the crystal structure. Equilibrium magnetic states of the model are described by two interacting antiferromagnetic sublattices with nonequal sublattice magnetizations, which allows for ferro-, antiferro-, and ferri-magnetic solutions. The analysis of calculated phase stability diagrams shows a thermodynamic path that qualitatively reproduces the experimentally observed phase transitions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)