Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.12: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
DC-Susceptibility of CeCu6−xAux at very low temperatures — •Andreas Hamann1, Tihomir Tomanic1, Hilbert v. Löhneysen1,2, and Oliver Stockert3 — 1Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe — 2Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe — 3MPI für chemische Physik fester Stoffe, 01187 Dresden
CeCu6 is a prototype heavy-fermion system that is rather well described by Fermi liquid (FL) theory. Au doping introduces long-range incommensurate antiferromagnetism for x > xc ≈ 0.1. In the vicinity of the quantum critical point xc significant deviations from FL theory have been observed in measurements of the specific heat, magnetic susceptibility and the electrical resistivity. In addition, highly unusual features were observed in inelastic neutron scattering [1,2]. In particular, the energy integrated dynamical as well as the statical susceptibility could be described by χ−1 ∝ (θ(q))α + c Tα with α = 0.75 [1]. We report measurements of the low-field dc-susceptibility χ(T) of CeCu5.9Au0.1 and CeCu5.85Au0.15 down to temperatures around 40 mK. Our data for x=0.1 show for T 200 mK deviations from the above χ−1 expression signaling a crossover for a smaller exponent α than previously found for higher T and B. For x=0.15 we see clear experimental evidence for the sharp onset of antiferromagnetic order below TN ≈ 82 mK for x = 0.15. We compare our data in detail with the previous work [1].
[1] A. Schröder et al., Nature 407, 6802 (2000)
[2] O. Stockert et al., Phys. Rev. Lett. 80, 5627 (1998)