Half-metallic ferrimagnetism in Mn 2CuGe

Abstract

We study magnetism properties and the electronic structure of a new Mn-based Heusler alloys Mn 2CuGe using ab initio electronic structure calculations. We take into account both possible L 2 1 structures (CuHg 2Ti and AlCu 2Mn types). The CuHg 2Ti-type structure is found to be energetically more favorable than the AlCu 2Mn-type structure and exhibits half-metallic ferrimagnetism. Calculations show that their total spin moment is − 1 μ B for a wide range of equilibrium lattice constants and magnetic moment mainly comes from the two Mn atoms, while the Cu atom is almost nonmagnetic. The small total moment comes from the antiparallel configurations of the Mn partial moments. And the CuHg 2Ti-type Mn 2CuGe alloy keeps a 100% of spin polarization at the Fermi level. Thus, the Mn 2CuGe is the compound of choice for further experimental investigations.