Structure and magnetic properties of Er3Fe29−xCrx compounds

Structure and magnetic properties of the Er3Fe29−xCrx compounds have been investigated by means of X-ray diffraction and magnetic measurements. It is found that all the Er3Fe29−xCrx compounds crystallize in a disordered Th2Ni17-type structure (space group P63/mmc) although the nominal atomic composition is 3:29. The lattice constants c increases and a decreases monotonically with increasing Cr content. When the Cr content increases, the Curie temperature Tc first increases, going through a maximum at around x = 2, then decreases. The saturation magnetization Ms decreases almost linearly with increasing Cr content. A first order magnetization process (FOMP) is observed for x = 2 and 3, the critical field Bcr of the FOMP is 4.52 T for x = 2 and 3.02 T for x = 3, respectively. All the compounds exhibit easy-plane type anisotropy at room temperature. The temperature dependence of the ac susceptibility measurement shows an anomaly at around 150 K, which is attributed to the temperature-induced domain wall movement under excitation of the external field for x = 0-3 and to a spin reorientation transition from the easy-plane type to the easy-axis type for x = 4, respectively.