Magnetic and transport anomalies inR2RhSi3(R=Gd, Tb, and Dy) resembling those of the exotic magnetic materialGd2PdSi3

We have carried out magnetization, heat-capacity, electrical, and magnetoresistance measurements (2–300 K) for the polycrystalline form of intermetallic compounds, $R_2\mathrm{RhS}{\mathrm{i}}_3(R=\mathrm{Gd}$, Tb, and Dy), forming in a $\mathrm{Al}{\mathrm{B}}_2$-derived hexagonal structure with a triangular $R$ network. This work was primarily motivated by a revival of interest on $\mathrm{G}{\mathrm{d}}_2\mathrm{PdS}{\mathrm{i}}_3$ after about two decades in the field of topological Hall effect due to magnetic skyrmions. We report here that these compounds are characterized by double antiferromagnetic transitions $(T_N=13.5$ and 12 K for Gd, 13.5 and 6.5 K for Tb, 6.5 and 2.5 K for Dy), but antiferromagnetism seems to be quite complex. The most notable observations common to all these compounds are as follows: (i) There are many features in the data mimicking those seen for $\mathrm{G}{\mathrm{d}}_2\mathrm{PdS}{\mathrm{i}}_3$, including the two magnetic transitions and the magnetic-field-induced changes in isothermal magnetization as though there are two metamagnetic transitions well below $T_N$. In view of such a resemblance of the properties, we speculate that these Rh-based materials offer a good playground to study topological Hall effect in a centrosymmetric structure, with its origin lying in triangular lattice of magnetic $R$ ions. (ii) There is an increasing contribution of electronic scattering with decreasing temperature towards $T_N$ in all cases, similar to $\mathrm{G}{\mathrm{d}}_2\mathrm{PdS}{\mathrm{i}}_3$, thereby serving as examples for a theoretical prediction for a classical spin-liquid phase in metallic magnetic systems due to geometrical frustration.