Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: CE: Heavy Fermions
TT 26.11: Vortrag
Mittwoch, 24. März 2010, 16:45–17:00, H21
Study of the temperature dependence of the magnetic excitations in CeCu2Ge2 — •Astrid Schneidewind1, Oliver Stockert2, Karin Schmalzl3, Enrico Faulhaber1, Micha Deppe2, and Michael Loewenhaupt4 — 1Joint Research Group Helmholtz-Zentrum Berlin - Technische Universität Dresden, Garching, Germany — 2Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — 3Jülich Centre for Neutron Science at Institut Laue-Langevin, Grenoble, France — 4Institut für Festkörperphysik, Technische Universität Dresden, Dresden, Germany
Long-range antiferromagnetic order establishes in the heavy fermion compound CeCu2Ge2 below TN = 4.15 K with an amplitude modulated structure and an ordering wave vector QAF = (0.28 0.28 0.543) [1]. Due to the Kondo effect the ordered moment is slightly reduced to m ≈ 1.0 µB at low temperatures [1].
We performed inelastic neutron scattering on a CeCu2Ge2 single crystal to study the low energy magnetic excitations in the ordered state. At lowest temperatures, dispersive spin waves have clearly been observed. At the magnetic zone centre the spin waves are gapped with Δ E ≈ 0.55 meV. The excitation spectrum changes with increasing temperatures and the gap closes giving rise to quasielastic scattering just below TN. The distinct behaviour of the magnetic excitation spectra can be related to the different magnetically ordered phases in CeCu2Ge2.
[1] A. Krimmel et al., Phys. Rev. B 55 (1997) 6416.