First-principles study of the lattice instabilities in Mn2NiX (X = Al, Ga, In, Sn) magnetic shape memory alloys
2015 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 3, 035401- p.Article in journal (Refereed) Published
Using first-principles based density functional theory, we have investigated the structural instabilities in the austenite phases of Mn2NiX (X = Al, Ga, In, Sn) magnetic shape memory alloys. A complete softening is observed in the acoustic TA(2) branches for all the materials along [xi xi 0] directions leading to instability in the austenite structure which effectively stabilizes into martensitic structure. The reasons behind this softening are traced back to the repulsion from the optical T-2g branches and to the nesting features in the Fermi surfaces. The vibrational density of states, the force constants and the elastic moduli are also computed and analyzed, which reconfirm the underlying mechanism behind the instabilities. The results indicate that the phonon anomalies are related to the occurrence of possible pre-martensitic phases which can be quite complex.
Place, publisher, year, edition, pages
2015. Vol. 27, no 3, 035401- p.
shape memory alloys, lattice dynamics, Fermi surface
Other Physics Topics
IdentifiersURN: urn:nbn:se:uu:diva-245358DOI: 10.1088/0953-8984/27/3/035401ISI: 000348493400009PubMedID: 25537964OAI: oai:DiVA.org:uu-245358DiVA: diva2:791382