Fe2MnGe: A hexagonal Heusler analogue

Abstract We synthesized bulk polycrystalline samples of Fe 2 MnGe using arc-melting and vacuum annealing. Our experimental investigations revealed that Fe 2 MnGe crystallizes in a hexagonal DO 19 phase at room temperature, in analogy with its “parent” compound Fe 3 Ge. We find a large saturation magnetization, even larger than that predicted for the tetragonal phase, of approximately 5 μ B /f.u. at T  = 5 K, with a Curie temperature of T c ∼505 K. The large moment and magnetocrystalline anisotropy, along with the possibility of half-metallicity presents Fe 2 MnGe as a strong candidate for spin-transfer-torque RAM and other spintronic applications. We do not find evidence for the cubic or tetragonal phases predicted by first-principles theory during these investigations. However, our neutron diffraction investigations were suggestive of a low temperature structural transformation.