Field suppression of the heavy-fermion state inCeRu2Si2

Abstract

Specific-heat measurements have been performed on a single-crystalline sample of the heavy-fermion compound ${\mathrm{CeRu}}_2$ ${\mathrm{Si}}_2$ in strong magnetic fields up to 20 T along the tetragonal axis in the temperature interval 1.5<T<30 K. The linear electronic term in the specific heat (γ) passes through a pronounced maximum at a field ${\mathit{B}}^{\mathrm{*}}$≃7.8 T, where the metamagneticlike transition occurs. For fields above ${\mathit{B}}^{\mathrm{*}}$, the mass enhancement decreases gradually, resulting in a reduction of the effective mass at 20 T by ∼80% with respect to the zero-field value. In the high-field region, the data have been analyzed using a simple single-resonance-level model.