Low-energy magnetic excitations of CeCu₂Ge₂ investigated by inelastic neutron scattering

CeCu2Ge2, the magnetic counterpart of the heavy-fermion superconductor CeCu2Si2, exhibits an antiferromagnetic ground state below T-N = 4.15 K with an incommensurate propagation vector of t = (0.28 0.28 0.54). The magnetism is determined by local Ce 4f-moments and the ordering RKKY interaction as well as the onset of Kondo screening by conduction electrons. Tuning the energy scale of the Kondo effect and RKKY interaction towards enhanced Kondo screening may result in quantum critical phenomena at low temperature. While the existence of quantum critical phenomena induced by external pressure or chemical substitution is well known, the situation is less clear for magnetic field tuning. We will present an investigation of the spin excitation spectrum in magnetic field by inelastic neutron scattering and compare it to mean-field (McPhase) simulations of the antiferromagnetic spin wave excitation spectrum. We argue that our data can be described by the presence of spin wave excitations