Previous studies have pointed to a heavy-electron state in CePtSi with a strongly enhanced electronic specific heat. We have explored the heat capacity, susceptibility and resistivity and the overall emerging picture is that magnetic ordering is avoided by accident: the entire 6fold energy level of the Hund¿s rule J=5/2 Ce ground state is available to the 4f electron, which brings about a spin degeneracy and entropy that avoids magnetic order in this system, in spite of the full Ce3+ effective paramagnetic moment. There is a strong Kondo action evident from the high-temperature resistivity, while at low temperatures the 4f electron scattering rate is modelled according to that of a marginal Fermi liquid. We propose to perform inelastic neutron scattering in order to confirm the picture obtained from heat capacity studies, as well as low-temperature muSR on CePtSi and LaPtSi.
