In this work the physical properties of the intermetallic compound $\mathrm{Tb}\mathrm{Rh}{\mathrm{In}}_5$ were investigated by means of temperature-dependent magnetic susceptibility, electrical resistivity, heat-capacity, and resonant x-ray magnetic diffraction experiments. $\mathrm{Tb}\mathrm{Rh}{\mathrm{In}}_5$ is an intermetallic compound that orders antiferromagnetically at $T_N=45.5\mathrm{K}$, the highest ordering temperature among the existing $R\mathrm{Rh}{\mathrm{In}}_5$ (1-1-5, $\mathrm{R}=\mathrm{rare}$ earth) materials, which in contrast to what is expected from a de Gennes scaling along the $R\mathrm{Rh}{\mathrm{In}}_5$ series. The x-ray resonant diffraction data have allowed us to solve the magnetic structure of $\mathrm{Tb}\mathrm{Rh}{\mathrm{In}}_5$. Below $T_N$, we found a commensurate antiferromagnetic structure with a propagation vector $(1∕2,0,1∕2)$ and the Tb moments oriented along the $c$ axis. Strong (over two orders of magnitude) dipolar enhancements of the magnetic Bragg peaks were observed at both Tb absorption edges $L_{\mathit{II}}$ and $L_{\mathit{III}}$, indicating a fairly high polarization of the Tb $5d$ levels. Using a mean-field model including an isotropic first-neighbor exchange interaction $\left(J_{R\text{−}R}\right)$ and the tetragonal crystalline electrical field (CEF), we evaluate the influence of the CEF effects in the physical properties of $\mathrm{Tb}\mathrm{Rh}{\mathrm{In}}_5$. The results reported here seem to corroborate a general trend of CEF-driven effects on $T_N$ along the $R\mathrm{Rh}{\mathrm{In}}_5$ series.

• Received 21 February 2006

DOI:https://doi.org/10.1103/PhysRevB.74.214404