Effect of temperature and compositional changes on the phonon properties of Ni-Mn-Ga shape memory alloys

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dc.contributor.authorEner, Sen_AU
dc.contributor.authorNeuhaus, Jen_AU
dc.contributor.authorPetry, Wen_AU
dc.contributor.authorMole, RAen_AU
dc.contributor.authorHradil, Ken_AU
dc.contributor.authorSiewert, Men_AU
dc.contributor.authorGruner, MEen_AU
dc.contributor.authorEntel, Pen_AU
dc.contributor.authorTitov, Ien_AU
dc.contributor.authorAcet, Men_AU
dc.date.accessioned2014-04-17T02:20:21Zen_AU
dc.date.available2014-04-17T02:20:21Zen_AU
dc.date.issued2012-10-11en_AU
dc.date.statistics2014-04-17en_AU
dc.description.abstractWe report on the vibrational properties of the ferromagnetic shape memory alloy system Ni-Mn-Ga in its stoichiometric Ni(2)MnGa and off-stoichiometric Ni(49)Mn(32)Ga(19) compositions. Elastic and inelastic neutron scattering measurements at different temperatures are presented with a focus on the austenite phase and compared to first-principles calculations. The overall behavior of the full phonon dispersion is similar for both compositions with remarkable exceptions for the TA(2)[xi xi 0] acoustic branch and optical phonon branches. Less dispersion is found in the optical phonons for Ni(49)Mn(32)Ga(19) in the whole reciprocal space when compared to Ni(2)MnGa and is explained by the occupation of regular Ga sites by excess Mn atoms. A pronounced softening in the TA(2)[xi xi 0] phonon branch within the austenite phase is observed in both samples when approaching the martensitic transition. Its location in reciprocal space reveals the martensitic transition mechanism. The austenite L2(1) structure transforms to the tetragonal modulated martensite structure by shuffling (110) planes in the [1 $(1) over bar $0] direction, similarly to what has been observed at the martensitic transitions of the d(1) and d(2) transition metals. Whereas the temperature dependence of the softening of the TA(2)[xi xi 0] phonons in the stoichiometric sample coincides perfectly with the magnetic and structural transitions, this is not the case for the off-stoichiometric sample. Here the relation between the magnetic ordering and the vibrational properties is still an open question. © 2012, American Physical Society.en_AU
dc.identifier.articlenumber144305en_AU
dc.identifier.citationEner, S., Neuhaus, J., Petry, W., Mole, R., Hradil, K., Siewert, M., Gruner, M. E., Entel, P., Titov, I., & Acet, M. (2012). Effect of temperature and compositional changes on the phonon properties of Ni-Mn-Ga shape memory alloys. Physical Review B, 86(14), Article Number 144305. doi:10.1103/PhysRevB.86.144305en_AU
dc.identifier.govdoc4777en_AU
dc.identifier.issn1098-0121en_AU
dc.identifier.issue14en_AU
dc.identifier.journaltitlePhysical Review Ben_AU
dc.identifier.urihttp://dx.doi.org/10.1103/PhysRevB.86.144305en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/5448en_AU
dc.identifier.volume86en_AU
dc.language.isoenen_AU
dc.publisherAmerical Physical Societyen_AU
dc.subjectFerromagnetismen_AU
dc.subjectNeutronsen_AU
dc.subjectMagnetic fieldsen_AU
dc.subjectMagnetismen_AU
dc.subjectMartensiteen_AU
dc.subjectCrystalsen_AU
dc.titleEffect of temperature and compositional changes on the phonon properties of Ni-Mn-Ga shape memory alloysen_AU
dc.typeJournal Articleen_AU
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