Incommensurate modulations in stoichiometric Ni2MnGa ferromagnetic shape memory alloy: An overview

Abstract

This article presents a brief overview of our recent work on the nature of long period modulation in the premartensite and martensite phases of Ni2MnGa ferromagnetic shape memory alloy using high resolution synchrotron x-ray powder diffraction patterns. The commensurate structure model using the Pnnm space group is unable to account for the peak positions of the satellite reflections that appear due to modulations correctly. LeBail and Rietveld refinements using the (3+1)-D super space group $Immm(00\gamma )s00$ show that the peak positions of all the reflections, including the satellites, can be explained satisfactorily using incommensurate modulations for both the premartensite and martensite phases. The incommensurate modulation vectors are found to be q= 0.33761(5)c* = (1/3+$\delta$1)c* and 0.43160(3)c*= (3/7+$\delta$2)c*, where $\delta$1 and $\delta$2 are the degrees of incommensuration for the premartensite and martensite phases, respectively. The periodicity of the closest rational approximant of the premartensite and martensite phases are confirmed to be 3M and 7M, respectively, in agreement with single crystal diffraction results.

arXiv commentarXiv admin note: text overlap with arXiv:1405.3478

References in corpus (5)

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Cited by in corpus (6)

• Premartensite to martensite transition and its implications on the origin of modulation in Ni2MnGa ferromagnetic shape memory alloy
• Robust Bain distortion in the premartensite phase of platinum substituted Ni2MnGa magnetic shape memory alloy
• Adaptive modulation in Ni2Mn1.4In0.6 magnetic shape memory Heusler alloy
• Strain and order-parameter coupling in Ni-Mn-Ga Heusler alloys from resonant ultrasound spectroscopy
• Robust evidence for the stabilization of the premartensite phase in Ni-Mn-In magnetic shape memory alloys by chemical pressure
• Precursor of the premartensite in Ni2MnGa magnetic shape memory alloy: A pair distribution function study