Electronic structure, magnetic properties and martensitic transformation in all-d-metal Heusler alloys Zn2YMn (Y = Fe, Co, Ni, Cu)

The site preference, electronic structure, magnetic properties and martensitic transformation of all-d-metal Heusler alloys Zn2YMn (Y = Fe, Co, Ni, Cu) have been investigated by first-principles calculations. In these alloys L21 structure is found to be more stable compared with XA, in which two Zn atoms prefer occupying the equilibrium A, C sites in the lattice. The total spin moments of Zn2YMn are all larger than 3μB and mainly come from the contribution of Mn. The contributions from Zn atoms are small for its low-lying d states, which do not hybridize with the d states of other atoms directly. Further calculation reveals that the tetragonal martensitic type Zn2YMn (Y = Fe, Co, Ni) can relax the total energy and are more stable than the cubic phase. The energy difference ΔEM between the cubic austenite and tetragonal martensite is as high as 0.31 eV in Zn2FeMn and decreases as Y atom varies from Fe to Ni. In martensitic type Zn2FeMn and Zn2CoMn, a quite large c/a ratio is observed, which is preferable for transformation strain effect.