Magnetic and transport anomalies in R2RhSi3 (R= Gd, Tb, and Dy), resembling those of an exotic magnetic skyrmion Gd2PdSi3.

We have carried out magnetization, heat capacity, electrical and magnetoresistance measurements (2-300 K) for the polycrystalline form of intermetallic compounds, R2RhSi3 (R= Gd, Tb, and Dy), forming in a AlB2 derived hexagonal structure with a triangular R network. This work was primarily motivated by a revival of interest on Gd2PdSi3 after about two decades in the field of Toplogical 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 for Dy), but antiferromagnerism seems to be complex. The most notable observations common to all these compounds are: (i) There are many features in the data mimicking those seen for Gd2PdSi3, including the two 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 toplogical 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 Gd2PdSi3, thereby serving as examples for a theoretical prediction for a classical spin-liquid phase in metallic systems due to geometrical frustration.