Neutron scattering study of the heavy-fermion compound CeRu 2 Si 2

TLDR: 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.

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 KlTl90 K) the magnetic response, Im(\ensuremath{\chi}/\ensuremath{\omega}), is well described by a quasielastic Lorentzian as a function of energy. The half-width \ensuremath{\Gamma} of the Lorentzian follows a \ensuremath{\surd}T law. At low temperatures (Tl20 K), the magnetic response, Im(\ensuremath{\chi}/\ensuremath{\omega}), seems to be better described by an inelastic peak. The half-width \ensuremath{\Gamma} remains temperature independent down to the lowest temperature (T\ensuremath{\simeq}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 (\ensuremath{\sim}60 K) but they saturate at T\ensuremath{\simeq}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.