Magnetic excitations in heavy-fermion CePd2Si2

We have studied the magnetic interactions of single-crystalline CePd2Si2 by measurements of the electrical resistivity, specific heat, thermal expansi on, magnetic susceptibility, and elastic and inelastic neutron scattering. In the paramagnetic phase the system is characterized by Kondo-type spin fl uctuations which give rise to a strong quasielastic signal in the inelastic neutron scattering cross section. Below the antiferromagnetic ordering tem perature (T-N= 8.5 K), the quasielastic signal coexists with spin-wave exci tations. The spin waves are strongly dispersive, with a minimum energy of 0 .83 meV at the magnetic zone center k=(1/2,1/2,0). The dispersion can be de scribed in terms of a two-sublattice model with a reduced magnetic exchange interaction and a strong damping of the spin waves due to Kondo screening. The volume dependence of the magnetic interactions has been analyzed using the Gruneisen parameters in order to study the magnetic interactions close to the quantum critical point, which is reached at an applied pressure of about 30 kbar.