Siewert, Mario; Gruner, Markus Ernst; Dannenberg, Antje; Chakrabarti, Aparna; Herper, Heike; Wuttig, Manfred; Barman, S. R.; Singh, S.; Al-Zubi, A.; Hickel, T.; Neugebauer, J.; Gillessen, M.; Dronskowski, R.; Entel, Peter:

Designing shape-memory Heusler alloys from first-principles

In: Applied Physics Letters, Jg. 99 (2011) ; Nr. 19, S. 191904 (3p)
ISSN: 1077-3118
Zeitschriftenaufsatz / Fach: Physik
Fakultät für Physik » Theoretische Physik
Abstract:
The phase diagrams of magnetic shape-memory Heusler alloys, in particular, ternary Ni-Mn-Z and quarternary (Pt, Ni)-Mn-Z alloys with Z = Ga, Sn, have been addressed by density functional theory and Monte Carlo simulations. Finite temperature free energy calculations show that the phonon contribution stabilizes the high-temperature austenite structure while at low temperatures magnetism and the band Jahn-Teller effect favor the modulated monoclinic 14M or the nonmodulated tetragonal structure. The substitution of Ni by Pt leads to a series of magnetic shape-memory alloys with very similar properties to Ni-Mn-Ga but with a maximal eigenstrain of 14%.