Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 17: Heavy Fermions

TT 17.8: Talk

Wednesday, March 28, 2007, 15:45–16:00, H18

Pressure dependence of the characteristic Kondo temperature of YbRh₂Si₂ — •Gabriel Alejandro Dionicio, Heribert Wilhelm, Julia Ferstl, Christoph Geibel, and Frank Steglich — Max-Planck-Institute for Chemical Physics of Solids

Several anomalies were observed in the electrical resistivity of YbRh₂Si₂ as a funtion of the pressure,namely, T_N and maxima at T_max and T_max^low. The engative logarithmic temperature dependence of the electrical resistivity ρ (T) for T>T_max and for T>T_max^low indicates that a combined incoherent Kondo scattering on the ground state and the excited CEF-levels are responsible for these anomalies. Therefore, we attempt to infer the pressure dependence of the characteristic Kondo temperature T_K(p) of YbRh₂Si₂ by means of a simple model that considers the effect of the orbital degeneracy on a dense Kondo state and the compressible Kondo lattice model. T_K(p) is compared with the pressure dependence of the Néel temperature T_N(p), in particular in the pressure range 4 GPa <p< 9 GPa where T_N(p) shows a quasi-pressure independent behavior.