Neutron scattering study of the heavy-fermion compoundCeRu2Si2

Abstract

We have performed inelastic-neutron-scattering experiments on single crystals of the heavy-fermion compound ${\mathrm{CeRu}}_2$ ${\mathrm{Si}}_2$. At intermediate temperatures (25 K<T<90 K) the magnetic response, Im(χ/ω), is well described by a quasielastic Lorentzian as a function of energy. The half-width Γ of the Lorentzian follows a √T law. At low temperatures (T<20 K), the magnetic response, Im(χ/ω), seems to be better described by an inelastic peak. The half-width Γ remains temperature independent down to the lowest temperature (T≃1.7 K) and amounts about 1.2 meV yielding a Kondo temperature $T_K$=14 K. The other important result we are presenting is the existence of magnetic correlations with a modulation characterized by two incommensurate wave vectors ${\mathrm{k}}_1$=(0.3,0,0) and ${\mathrm{k}}_2$=(0.3,0.3,0). These magnetic correlations start to develop already at rather high temperatures (∼60 K) but they saturate at T≃15 K when the magnetic response becomes inelastic. So the hybridation of 4f electrons with conduction electrons seems to prevent the divergence of the magnetic correlations which otherwise would give rise to a long-range magnetic ordering.