Magnetic and transport anomalies in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>R</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>RhS</mml:mi><mml:msub><mml:mi mathvariant="normal">i</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow><mml:mspace width="4pt"/><mml:mo>(</mml:mo><mml:mrow><mml:mi>R</mml:mi><mml:mo>=</mml:mo><mml:mi>Gd</mml:mi></mml:mrow></mml:math>, Tb, and Dy) resembling those of the exotic magnetic material<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">G</mml:mi><mml:msub><mml:mi mathvariant="normal">d</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>PdS</mml:mi><mml:msub><mml:mi mathvariant="normal">i</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>
Ram Kumar, Kartik K. Iyer, P. L. Paulose, E. V. Sampathkumaran
Abstract
We have carried out magnetization, heat-capacity, electrical, and magnetoresistance measurements (2--300 K) for the polycrystalline form of intermetallic compounds, ${R}_{2}\mathrm{RhS}{\mathrm{i}}_{3}\phantom{\rule{4pt}{0ex}}(R=\mathrm{Gd}$, 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.