Electronic structure, magnetic properties and martensitic transformation in all-d-metal Heusler alloys Zn 2 YMn (Y = Fe, Co, Ni, Cu)

Abstract The site preference, electronic structure, magnetic properties and martensitic transformation of all-d-metal Heusler alloys Zn 2 YMn (Y = Fe, Co, Ni, Cu) have been investigated by first-principles calculations. In these alloys L2 1 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 Zn 2 YMn are all larger than 3μ B 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 Zn 2 YMn (Y = Fe, Co, Ni) can relax the total energy and are more stable than the cubic phase. The energy difference ΔE M between the cubic austenite and tetragonal martensite is as high as 0.31 eV in Zn 2 FeMn and decreases as Y atom varies from Fe to Ni. In martensitic type Zn 2 FeMn and Zn 2 CoMn, a quite large c/a ratio is observed, which is preferable for transformation strain effect.