Magnetic structure and enhanced TN of the rare-earth intermetallic compound TbRhIn5:: Experiments and mean-field model

In this work the physical properties of the intermetallic compound TbRhIn5 were investigated by means of temperature-dependent magnetic susceptibility, electrical resistivity, heat-capacity, and resonant x-ray magnetic diffraction experiments. TbRhIn5 is an intermetallic compound that orders antiferromagnetically at T-N=45.5 K, the highest ordering temperature among the existing RRhIn5 (1-1-5, R=rare earth) materials, which in contrast to what is expected from a de Gennes scaling along the RRhIn5 series. The x-ray resonant diffraction data have allowed us to solve the magnetic structure of TbRhIn5. 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-II and L-III, indicating a fairly high polarization of the Tb 5d levels. Using a mean-field model including an isotropic first-neighbor exchange interaction (J(R-R)) and the tetragonal crystalline electrical field (CEF), we evaluate the influence of the CEF effects in the physical properties of TbRhIn5. The results reported here seem to corroborate a general trend of CEF-driven effects on T-N along the RRhIn5 series.