Magnetic ordering in NdRhSn

A NdRhSn single crystal has been grown and investigated with respect to crystal structure and magnetic behavior. The hexagonal ZrNiAl-type crystal structure has been confirmed by the X-ray diffraction analysis. The magnetization and specific heat were measured as functions of temperature and magnetic field applied along the crystallographic a- and c-axes, Strong uniaxial magnetocrystalline anisotropy was observed with the c-axis as easy magnetization direction. Analysis of experimental data leads to the following scenario of magnetism in NdRhSn: The compound is paramagnetic at high temperatures. At 9.8 K, a transition from the paramagnetic state to antiferromagnetic (AF) ordering of the Nd magnetic moments takes place. The temperature interval of the AF-phase stability is narrow and, at 7.6 K, the magnetic moments in the compound condense to a ground state characterized by a spontaneous magnetization corresponding to about 2/3 of the value of the Nd3+ free-ion moment. This may be either due to crystal-field effects or to a complex magnetic structure. The results of ab initio calculations of the NdRhSn electronic structure confirmed that besides the stable Nd magnetic moment due the localized 4f-electrons only a very small magnetic moment of at most 0.1 μB is induced at the Rh site due to the polarized Rh 4d-electron states hybridizing with the Nd 5d-electron states, i.e. the Rh moment plays only minor role in the total balance of the magnetic moments in this compound.