Martensitic transition and structural modulations in the Heusler alloy Ni2FeGa

We have found two distinctive structural modulations altering evidently along with the martensitic transition (MT) in the Ni2FeGa alloy. The first one (q1), corresponding to the well-known phonon anomalies in the [ζζ0] TA2 branch, occurs along the 〈110〉 direction. The second one (q2), an incommensurate modulation observed for the first time, occurs along the 〈211〉-direction. Both modulations change gradually with the premartensitic phonon softening and discontinuously with the MT. Anomalies in magnetic properties emerging around the MT have been briefly discussed.