Magnetostructural martensitic transformations with large volume changes and magneto-strains in all-d-metal Heusler alloys

摘要

The all-d-metal Mn2-based Heusler ferromagnetic shape memory alloysMn50Ni40-xCoxTi10 (x = 8 and 9.5) are realized. With a generic comparisonbetween d-metal Ti and main-group elements in lowering the transformationtemperature, the magnetostructural martensitic transformations are establishedby further introducing Co to produce local ferromagnetic Mn-Co-Mnconfigurations. A 5-fold modulation and (3, -2) stacking of [00 10] ofmartensite are determined by XRD and HRTEM analysis. Based on thetransformation, a large magneto-strain of 6900 ppm and a large volume change of-2.54% are observed in polycrystalline samples, which makes the all-d-metalmagnetic martensitic alloys of interest for magnetic/pressure multi-fielddriven applications.