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Zusammenfassung:
Elastic and inelastic neutron scattering studies of the Kondo lattice CeCu2Ge2 were performed. AtT N=4.1 K an incommensurate magnetic order develops with an ordering wave vectorq 0=(0.28, 0.28, 0.54) and an ordered moment µ s =0.74 µB. The crystalline electric field splits the 4f 1-J-multiplet of the Ce ion into a ground state doublet and a quartet at 191 K. The wave function of the ground state yields an ordered moment of 1.54µB. Thus, due to the onset of the formation of a Kondo singlet the magnetic moment is considerably reduced. The magnetic relaxation rate Λ was investigated via quasielastic neutron scattering. The temperature dependence of Λ(T) is characteristic of heavy-fermion systems with a high temperature square root dependence and a limiting low temperature value, yielding a Kondo temperatureT K≈10K. The quasielastic component of the scattered neutron intensities persists down to the lowest temperatures, well belowT N. This quasielastic line is regarded as a characteristic feature of heavy-fermion systems and corresponds to the enhanced value of the linear term of the specific heat.
