Crystal field excitations in the cubic compound Ce₃Rh₄Sn₁₃

The recent heat capacity measurements of Ce₃Rh₄Sn₁₃ have revealed a broad peak at 1 K with an entropy of 3R ln(2) per f.u., but no clear sign of any magnetic ordering down to 100 mK. In order to understand this anomalous heat capacity behaviour of Ce₃Rh₄Sn₁₃, we have carried out low- and high-energy inelastic neutron scattering measurements. Our high-energy studies reveal two well-resolved crystal field (CF) excitations at ∼9 meV and 38 meV. The observation of two CF excitations in the cubic structure of Ce₃Rh₄Sn₁₃ could be explained on the basis of tetragonal point symmetry of the Ce ions. Interestingly, the low-energy measurements apparently show, or are best described by, a quasi-elastic peak and an inelastic peak at ∼0.2 meV at 1.5 K, both of Lorentzian shape. We attribute the low-energy peak to Zeeman splitting of the ground state doublet, in the presence of short range magnetic ordering. Further, the low-energy peak explains the observed anomaly in the heat capacity.