In-situ high-energy x-ray diffuse-scattering study of the phase transition of Ni2MnGa single crystal under high magnetic field

The defects-related microstructural features connected to the premartensitic and martensitic transition of a Ni2MnGa single crystal under a high magnetic field of 50 KOe applied along the (1(bar 1)0) crystallographic direction of the Heusler phase were studied by the in-situ high-energy X-ray diffuse-scattering experiments on the high energy synchrotron beam line 11-ID-C of APS and thermomagnetization measurements. Our experiments show that a magnetic field of 50 KOe applied along the (1(bar 1)0) direction of the parent Heusler phase can promote the premartensitic transition of Ni2MnGa single crystal, but puts off martensite transition and the reverse transition. The premartensitic transition temperature (TPM) increases from 233 to 250 K (-40 to -23 C). The martensite transition start temperature (Ms) decreases from 175 to 172 K (-98 to -101 C), while the reverse transition start temperature (As) increases from 186 to 189 K (-87 to -84 C). The high magnetic field leads to a rapid rearrangement of martensite variants below the martensite transition finish temperature (Mf). The real transition process of Ni2MnGa single crystal under the high magnetic field was in-situ traced.