Lattice parameter values and magnetic properties for the Mn2GeTe4, Fe2GeTe4 and Fe2SnSe4 compounds

X-ray powder diffraction measurements, at room temperature, and magnetic susceptibility χ measurements, in the temperature range from 2 to 300 K, were made on polycrystalline samples of Mn2GeTe4, Fe2GeTe4 and Fe2SnSe4 compounds, which would be useful for spintronic device production. Magnetization M measurements at various temperatures were carried out on the Fe-compounds. From the analysis of the X-ray diffraction patterns, it was found that the Mn2GeTe4, Fe2GeTe4 and Fe2SnSe4 have orthorhombic structure, possibly an olivine structure-type (SG: Pnma No. 62, z = 4). It was found that Mn2GeTe4 has a Néel temperature of 30 K, shows mainly antiferromagnetic behavior with a weak superimposed ferromagnetic component which is attributed to spin canting. The resulting susceptibility χ versus T curves for Fe2GeTe4 and Fe2SnSe4 were found to have, in each case, a form which is typical of a ferromagnetic material with Curie temperatures TC of 149.9 and 301 K, respectively. The critical exponent β for the Fe-compounds were found to be very similar and close to the expected value for a ferromagnetic material, in the range 0.33–0.39. The values of the coercive field BC and the remanent magnetization Mr were found to vary nonlinearly with the temperature T.