Premartensite to martensite transition and its implications for the origin of modulation in N i2MnGa ferromagnetic shape-memory alloy
Singh S, Bednarcik J, Barman SR, Felser C, Pandey D (2015)
Publication Type: Journal article
Publication year: 2015
Journal
Book Volume: 92
Article Number: 054112
Journal Issue: 5
DOI: 10.1103/PhysRevB.92.054112
Abstract
We present results of a temperature-dependent high-resolution synchrotron x-ray powder diffraction study of sequence of phase transitions in Ni2MnGa. Our results show that the incommensurate martensite phase results from the incommensurate premartensite phase and not from the austenite phase assumed in the adaptive phase model. The premartensite phase transforms to the martensite phase through a first order phase transition with coexistence of the two phases in a broad temperature interval (∼40K), discontinuous change in the unit cell volume as also in the modulation wave vector across the transition temperature, and considerable thermal hysteresis in the characteristic transition temperatures. The temperature variation of the modulation wave vector q shows smooth analytic behavior with no evidence for any devilish plateau corresponding to an intermediate or ground state commensurate lock-in phase. The existence of the incommensurate 7M-like modulated structure down to 5 K suggests that the incommensurate 7M-like modulation is the ground state of Ni2MnGa and not the Bain distorted tetragonal L10 phase or any other lock-in phase with a commensurate modulation. These findings can be explained within the framework of the soft phonon model.
Involved external institutions
Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids
Germany (DE)
Deutsches Elektronen-Synchrotron DESY
Germany (DE)
UGC DAE Consortium for Scientific Research
India (IN)
Banaras Hindu University
India (IN)
Germany (DE)
Deutsches Elektronen-Synchrotron DESY
Germany (DE)
UGC DAE Consortium for Scientific Research
India (IN)
Banaras Hindu University
India (IN)
How to cite
APA:
Singh, S., Bednarcik, J., Barman, S.R., Felser, C., & Pandey, D. (2015). Premartensite to martensite transition and its implications for the origin of modulation in N i2MnGa ferromagnetic shape-memory alloy. Physical Review B - Condensed Matter and Materials Physics, 92(5). https://dx.doi.org/10.1103/PhysRevB.92.054112
MLA:
Singh, Sanjay, et al. "Premartensite to martensite transition and its implications for the origin of modulation in N i2MnGa ferromagnetic shape-memory alloy." Physical Review B - Condensed Matter and Materials Physics 92.5 (2015).
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