Understanding the martensitic phase transition of Ni-2(Mn1-xFex)Ga magnetic shape-memory alloys from theoretical calculations
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 17, 174112Article in journal (Refereed) Published
By using first principles in combination with atomistic spin dynamics calculational methods, we determine the temperature-dependent free energies of the L2(1)-and L1(0)-Ni-2(Mn1-xFex) Ga (0 <= x <= 1), including phonon vibrational and magnetic energies. The x-dependent martensitic phase transformation (MPT) temperature (T-M) and the Curie temperature (T-C) are well represented. It is found that, the abnormal nonmonotonic behavior of T-M similar to x mainly originates from the phonon vibrational free energy. The magnetic energy, which does not change the trend of T-M against x but decreases the driving force of the MPT, is indispensable as well to get reasonable T-M values. This insight provides a good understanding of the physical mechanisms driving the MPT of Ni-2(Mn1-xFex)Ga, and promotes the improvement of their magnetic shape memory properties.
Place, publisher, year, edition, pages
2015. Vol. 91, no 17, 174112
IdentifiersURN: urn:nbn:se:kth:diva-169254DOI: 10.1103/PhysRevB.91.174112ISI: 000355088000002ScopusID: 2-s2.0-84930226090OAI: oai:DiVA.org:kth-169254DiVA: diva2:821958
QC 201506162015-06-162015-06-122015-06-16Bibliographically approved