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Ni2MnGa(100) ferromagnetic shape memory alloy: A surface study

TitleNi2MnGa(100) ferromagnetic shape memory alloy: A surface study
Publication TypeJournal Article
Year of Publication2012
AuthorsD'Souza SW, Nayak J, Maniraj M, Rai A, Dhaka RS, Barman SR, Schlagel DL, Lograsso TA, Chakrabarti A
Journal TitleSurface Science
Volume606
Pages130-136
Date Published02
Type of ArticleArticle
ISBN Number0039-6028
Accession NumberWOS:000300458600006
Keywordscompound ni2mnga, crystal-structure, density functional theory, ferromagnetic shape memory alloy, field-induced strain, low energy electron diffraction, MARTENSITE, MARTENSITIC-TRANSFORMATION, mn2niga, ni-mn-ga, ni2+xmn1-xga, phase-transitions, photoemission spectroscopy, premartensitic transition, single-crystals, transition
Abstract

Ni2MnGa(100) single crystal studied using low energy electron diffraction (LEED) and ultraviolet photoemission spectroscopy (UPS) exhibits interesting modification of the surface properties that are mainly influenced by surface composition as well as intrinsic effects. In the martensite phase, the LEED spot profiles show presence of an incommensurate modulation for the stoichiometric surface. In contrast, a commensurate modulation is observed for Mn-excess Ni-Mn-Ga surface. A pre-martensite phase is identified at the surface. Both the surface martensitic and pre-martensitic transition temperatures decrease as the Mn content increases. The UPS spectra in the austenite phase exhibit systematic change in shape as a function of surface composition that can be related to changes in the hybridization between Ni and Mn 3d states. The spectra in the martensite phase exhibit interesting modifications near the Fermi level, which has been compared to density of states calculated for a modulated structure by ab-initio density functional theory. Intrinsic surface properties dissimilar from the bulk are enhanced hysteresis width of the martensite transition and increased pre-martensitic transition temperature. (C) 2011 Elsevier B.V. All rights reserved.
URL<Go to ISI>://WOS:000300458600006
DOI10.1016/j.susc.2011.07.023
Alternate JournalSurf. Sci.