Theoretical description of the colossal entropic magnetocaloric effect: Application to MnAs

We report on the theoretical investigations into the recently discovered colossal entropy change in MnAs under magnetic-field change in an isothermal process. The phenomenological model takes into account the exchange-Zeeman interactions, magnetoelastic interactions, the external pressure effect, and the magnetic-field dependence of the lattice entropy. The results show the fundamental role of the lattice entropy in the colossal entropy change for the MnAs compound. The best model parameters and their variation with pressure were determined.73