Understanding the phase transitions of the Ni2MnGa magnetic shape memory system from first principles
In: Physical Review Letters, Jg. 102 (2009) ; Nr. 3, S. 035702 (4pp)
Zeitschriftenaufsatz / Fach: Physik
The free energies of the austenite, the (modulated) premartensite and the unmodulated martensite of Ni2MnGa are determined using density functional theory and including quasiharmonic phonons and fixed-spin-moment magnons. This approach very well reproduces the complete phase sequence (martensite<-->premartensite<-->austenite) of stoichiometric Ni2MnGa as a function of temperature. By analyzing the relevant free energy contributions, we also understand the delicate interplay of phonons and magnons driving both phase transitions.