Heavy fermion systems in the presence of CEF: Thermal properties

Abstract

The effect of CEF on thermal properties of heavy fermion system CeRu 2Si 2 has been studied in the framework of infinite- U degenerate impurity Anderson model using slave-boson approach within 1 N expansion. The calculation of specific heat and thermal expansion coefficient reveal the presence of characteristic peaks in the low temperature regime. In the presence of crystalline electric field, an overall decrease is found in their values alongwith the shift of peaks towards high temperature side, which implies weakening in the heavy fermion character. However, the experimental data towards the low temperature side is found to be closer to the situation with Δ = 0 and that towards high temperature side, close to the case with Δ ≠ 0. The overall qualitative behavior is found to be consistent with the data.