Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 22: Correlated Electrons: Quantum-Critical Phenomena 2

TT 22.6: Talk

Wednesday, March 25, 2009, 11:15–11:30, HSZ 03

Tuning the magnetic behavior in Yb(Rh_1−xCo_x)₂Si₂ with Chemical Pressure — •Christoph Klingner, C. Krellner, C. Geibel, and F. Steglich — Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany

In recent years YbRh₂Si₂ has been intensively investigated due to its proximity to an antiferromagnetic quantum critical point (QCP). As expected for Yb-Kondo lattice compounds the magnetic ordering of YbRh₂Si₂ (T_N=70mK) is stabilized by applying pressure. The complementary method of doping with Cobalt results in chemical pressure allowing therefore an investigation of the magnetic phase diagram and the physical behavior of the stabilized antiferromagnetic ordered state. A thorough understanding of the physical properties of this series, particularly for small amounts of Cobalt doping, are of high interest to understand the phenomena at the QCP in YbRh₂Si₂. In this contribution we report on the growth of a series of single crystals Yb(Rh_1−xCo_x)₂Si₂ with concentrations x from 0 to 1. The crystallographic parameters as well as low temperature properties studied by resistivity, specific heat and magnetization measurements will be presented and compared to already existing pressure data on YbRh₂Si₂. The qualitative agreement of the magnetic phase diagrams obtained from hydrostatic and chemical pressure experiments can be shown. With increasing x the change of the physical properties of the series Yb(Rh_1−xCo_x)₂Si₂ can be understood originating from the interplay of the Kondo- and RKKY- dominated exchange interaction.