Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.55: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Hall Effect in YbRh2Si2 — •Sven Friedemann1, Niels Oeschler1, Silke Paschen1,2, and Frank Steglich1 — 1Max-Planck-Institut for Chemical Physics of Solids, Noethnitzer Strasse 40, 01187 Dresden, Germany — 2Vienna University of Technology, Karlsplatz 13, 1040 Wien, Austria
The heavy-fermion metal YbRh2Si2 exhibits pronounced non-Fermi liquid behaviour due to its vicinity to a quantum critical point (QCP). At zero magnetic field, the system orders antiferromagnetically at very low temperatures (TN=70 mK). By applying a small magnetic field, YbRh2Si2 is driven through the QCP towards the paramagnetic state. Currently, two scenarios for a system at this type of QCP are discussed: The spin-density-wave scenario at which heavy electrons are expected on both sides of the QCP and the locally QCP at which the heavy electrons on the paramagnetic side disintegrate into localised magnetic moments and light conduction electrons on the magnetic side of the QCP. The field-dependent Hall effect as a measure of the Fermi volume turns out to be the appropriate method to characterize the QCP in YbRh2Si2. Low-temperature Hall-effect measurements of YbRh2Si2 show a rapid change of the Fermi volume and thus strongly hint at the existence of a locally QCP with a small Fermi surface at the magnetic side and a large one at the paramagnetic side [1]. We present similar measurements of the Hall coefficient on YbRh2Si2 and on the reference substance LuRh2Si2 in an extended temperature range.
[1] S. Paschen et al., Nature 432, 881 (2004)