Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Correlated Electrons: Quantum-Critical Phenomena - Experiments

TT 59.8: Vortrag

Donnerstag, 14. März 2013, 17:15–17:30, H6

Influence of charge carrier doping on the T^∗-Scale in YbRh₂Si₂ — •M.-H. Schubert, Y. Tokiwa, H. S. Jeevan, E. Blumenröther, and P. Gegenwart — I. Physikalische Institut, Georg-August-Universtität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

YbRh₂Si₂ is a prototype heavy-fermion metal which displays a magnetic, field-induced antiferromagnetic (AF) quantum critical point (QCP). It has attracted much attention due to an additional low-energy scale T^⋆(B) merging at the QCP, whose origin is still under discussion. Here, we present our recent thermodynamic, magnetic and electrical transport measurements on different single crystalline samples of charge-carrier doped Yb(Rh_1−xT_x)₂Si₂ (T=Fe, Ni, Ru) at temperatures down to 15 mK and in magnetic fields up to 7 T. The partial substitution of Rh by either Fe or Ni introduces holes or electrons, respectively. The evolution of the single-ion Kondo scale is similar to isoelectronic Co substitution in accordance with the chemical pressure effect. However, while chemical pressure has little influence on T^⋆(B) in isoelectronic doped samples, we observe a drastic reduction or increase of B^⋆(T=0) by Fe- or Ni-doping, respectively. As the AF order is completely suppressed by Fe-doping, a heavy Fermi liquid ground state (without the T^⋆(B) anomaly) is observed. These results are compared to measurements on samples where Rh is partially substituted by Ru. Here the chemical pressure effect is minimized in order to investigate the pure charge doping effect.

Work supported by the DFG research unit 960 (Quantum phase transitions).