We compare the magnetic properties of 3d (Fe and Co) and 4d (Ru and Rh) transition metals doped MnNiGe using the combined results of magnetization and ab initio calculations. The alloys crystallize in austenite Ni2In-type hexagonal phase (space group: P63/mmc) with insignificant difference in the lattice parameters. Mn0.7Fe0.3NiGe and Mn0.7Co0.3NiGe exhibit spin-glass behavior, resulting from the competing ferro-and antiferromagnetic interactions. These alloys exhibit spontaneous exchange bias field of about Oe and 323 Oe, respectively. From the 4d-metal doped alloys, Mn0.7Ru0.3NiGe shows glassy behavior while long-range ferromagnetic order is confirmed in Mn0.7Rh0.3NiGe. In Mn0.7Rh0.3NiGe, in agreement with experiment and the theoretical calculations, the ground state is confirmed to be ferromagnetic because of the FM exchange interactions of the Mn magnetic moments. But in Mn1-x(Fe,Co,Ru)xNiGe alloys the calculations revealed the competing and comparable FM and AFM exchange interaction parameters, resulting in the formation of spin-glassy characteristics.
- ab initio calculations
- Heusler alloys