Exotic Nd 4f electron magnetism in Nd2RhSi3

The compound, Nd₂PdSi₃ belonging to R₂PdSi₃ family (R = rare-earths) has been known to exhibit exotic behavior due to unusual Nd 4f-hybridization. Here, we study the electronic properties of Nd₂RhSi₃ employing ac and dc magnetization, heat-capacity, electrical resistivity and magnetoresistance measurements, as Nd 4f-hybridization is expected to be slightly different due to the changes in the 4d element. The experimental results establish that, like the Pd analogue, this compound also exhibits ferromagnetic ordering at a rather high temperature of 16.5 K, unlike many other rare-earth members of this family which are antiferromagnetic, with a complex magnetism at further lower temperatures (< ∼10 K). There are differences in the measured properties with respect to the Pd analogue, the most important one being the observation of spin-glass features at a temperature significantly higher than the Curie temperature. This is attributed to a gradual evolution of cluster magnetism with decreasing temperature. We infer that the changes in Nd 4f hybridization due to Rh 4d (instead of Pd 4d) plays a role in some fashion for such differences. These properties are attributed to the competing magnetic ground states due to geometrical frustration arising out of triangular arrangement of Nd ions with a bond disorder.