Antiferromagnetism weakening with Y-substitution in the TbRhIn${}_5$ intermetallic system

Abstract

We report measurements of the temperature dependence specific heat, magnetic susceptibility in single crystals of the series of intermetallic compounds Tb${}_{1-x}$Y${}_x$RhIn${}_5$ (nominal concentrations $x=0.15,0.30,0.40,0.50$ and $0.70$). A mean field approximation to simulate the macroscopic properties along the series has been used. Neutron diffraction data in powdered sample of nominal concentration Tb${}_{0.6}$Y${}_{0.4}$RhIn${}_5$ reveal AFM propagation vector $k=[\frac{1}{2}0\frac{1}{2}]$ with the magnetic moments oriented close to the tetragonal \textit{c} axis. We discuss the role of combined effects of crystalline electric field (CEF) perturbations and dilution in the magnetic properties evolution with Y content. In particular, we suggest that changes in the Tb-In first neighbors distances, i.e. the TbIn${}_3$ cuboctahedra distortion, are responsible for changes in the Tb crystalline potential and the possible reorientation of Tb magnetic moments for $x>$0.4. This reflects non negligible variations of the $B_n^m$ crystal field parameters and the energy levels splitting with \textit{x}.