Evidence for a hybridization gap in noncentrosymmetric CeRuSi3

Inelastic neutron scattering (INS) and specific heat measurements have been performed on the intermediate valence compound CeRuSi3, which is isostructural to the noncentrosymmetric pressure-induced superconductors CeRhSi3, CeIrSi3, and CeCoGe3. INS measurements at 7 K reveal a broad peak at (58.5 ± 1.4) meV, while at 300 K, broad quasielastic scattering is observed. This indicates a large Kondo temperature of TK ~ 680 K. The magnetic contribution to the specific heat (Cmag) has a value of γ = 62.5(1) mJ/molK2 at low temperatures and above about 100 K can be well accounted for by the Coqblin-Schrieffer model with a characteristic temperature of T0 = 680 K, which is further evidence that CeRuSi3 is in the intermediate valence regime.