Complex magnetic behavior in the novel Kondo lattice compound CeRhSn ₃

We report the magnetic and transport properties of a new ternary intermetallic compound, CeRhSn₃, using magnetic susceptibility, magnetization, specific heat, electrical resistivity, muon-spin relaxation (μSR) and neutron diffraction investigations. The dc magnetic susceptibility data reveal two magnetic phase transitions at 0.9 and 4K. The overall behavior of dc susceptibility and magnetization indicates a ferrimagnetic-type phase transition near 4K. The specific heat data also exhibit sharp λ-type anomalies at 1 and 4K. The behavior of the specific heat anomaly under the application of a magnetic field suggests that the 1K transition is probably related to a transition from a ferri-to a ferromagnetic state. The low temperature specific heat exhibits an enhanced Sommerfeld coefficient γ (∼100mJmol^{- 1}K^{- 2}) due to the formation of a moderate heavy fermion state. The resistivity of CeRhSn₃ demonstrates an interplay between the RKKY and Kondo interactions which is further modified by the presence of the crystal electric field. Interestingly, the resistivity of the nonmagnetic reference compound, LaRhSn₃, is found to increase with decreasing temperature. Further, the onset of long-range magnetic order below 1K is confirmed from our μSR study on CeRhSn₃. However, the 4K transition is not detected in the μSR and low temperature neutron diffraction data. Analysis of the dc magnetic susceptibility data within the framework of a two-sublattice model of ferrimagnetism supports the ferrimagnetic-type transition at 4K in CeRhSn₃. We have observed an unusual frequency dependence of the peak near 4K in the ac susceptibility, which shows that the transition temperature shifts toward the lower temperature side with increasing frequency.