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TT: Tiefe Temperaturen

TT 35: Correlated Electrons - Quantum Critical Phenomena

TT 35.3: Vortrag

Mittwoch, 9. März 2005, 11:45–12:00, TU H104

Quantum Critical Behavior in Yb_1−xLa_xRh₂Si₂ Studied by Low Temperature Resistivity in Magnetic Fields and under High Pressure — •Michael Nicklas, Julia Ferstel, Christoph Geibel, and Frank Steglich — Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Str.40, 01187 Dresden

The stoichiometric heavy fermion system YbRh₂Si₂ is situated close to a quantum critical point (QCP). At zero magnetic field very weak antiferromagnetic order occurs at T_N=70 mK. Substitution of Si by larger Ge reduces T_N, however, difficulties in sample preparation prevent a complete suppression of T_N by Ge-doping. An alternative route to suppress the antiferromagnetic order is the partial substitution of Yb by larger La in Yb_1−xLa_xRh₂Si₂.

We present pressure studies of the electrical resistivity of the paramagnetic 5% and 10% La substituted Yb_1−xLa_xRh₂Si₂. Applying pressure reduces the unit cell volume again and the system can be tuned through the critical volume. However, substitution of the magnetic ion by non-magnetic La at the Yb-site has more subtle effects and acts not just as chemical pressure on the system.