Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.11: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Magnetotransport across the field-induced quantum phase transition in CeCu5.8Au0.2 — •Marc Uhlarz1, Moritz Röger1, Tihomir Tomanic1, and Hilbert v. Löhneysen1,2 — 1Physikalisches Institut, Universität Karlsruhe (TH), D-76128 Karlsruhe — 2Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe
We report on magnetoresistivity and Hall effect of CeCu0.58Au0.2, magnetic field B applied along the hard direction (b axis in orthorhombic notation) and current I along the a axis. At B=0, CeCu0.58Au0.2 orders antiferromagnetically below TN=0.25 K [1]. As observed previously [1], the longitudinal electrical resistivity ρxx(T) rises towards lower T below TN for current directions containing a component of the magnetic ordering vector Q=(0.625, 0, 0.275). With increasing B, the rise of ρxx(T) becomes smaller and TN shifts to lower T, vanishing at Bc=3.6 T. Likewise, the field derivative of the transverse resistivity dρxy/dB (independent of B at high temperatures) becomes field-dependent in the vicinity of Bc below TN. This signals (in a simple single-band picture) an increase of the effective carrier concentration when B exceeds the critical field Bc of antiferromagnetic order. Our data will be compared to recent experiments on YbRh2Si2, where a kink of the Hall coefficient RH at Bc was inferred for T → 0 from the gradual change of slope of ρxy(B) for finite T, becoming more pronounced for T → 0 [2].
[1] H. v. Löhneysen et al., Eur. Phys. J. B 5 (1998) 447
[2] S. Paschen et al., Nature 432 (2004) 881.