The magnetic, electronic and optical properties of HoRhGe

The physical properties of polycrystalline HoRhGe have been studied experimentally and theoretically. The compound orders antiferromagnetically with a Néel temperature (T_N) of 5.5K. It shows a large negative magnetoresistance (MR) of 25% at T_N, for a field of 50kOe. However, at 2K and in lower fields, the MR is found to be positive with a magnitude of about 12%. The magnetocaloric effect has been estimated from both magnetization and heat capacity data and found to be large compared to many potential refrigerant materials in the same temperature range. The optical conductivity calculated theoretically from the ab initio results is in agreement with experimental values. The electronic structure calculations with the LSDA+U method accounting for the strong electronic correlations in the 4f shell of holmium show that the Ho 4f electronic states play a major role in determining its magnetic, electronic and optical properties.