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TT: Fachverband Tiefe Temperaturen

TT 27: CE: Poster Session

TT 27.14: Poster

Mittwoch, 24. März 2010, 14:00–18:00, Poster D1

Electron spin resonance of the Yb 4f-moment in Yb(Rh_1−xCo_x)₂Si₂ — •Thomas Gruner, Jörg Sichelschmidt, Christoph Klingner, Cornelius Krellner, Christoph Geibel, and Frank Steglich — Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany

We present a detailed electron spin resonance (ESR) study on a series of single crystals Yb(Rh_1−xCo_x)₂Si₂ with Cobalt concentrations x from 0 to 1. All compositions show well defined ESR spectra which can be ascribed to a bulk Yb³⁺ resonance. The pure system YbRh₂Si₂ is located in the vicinity of an antiferromagnetic quantum critical point. The magnetic ordering of this system (T_N =72 mK) is stabilized by pressure as it is expected for Yb-Kondo lattice compounds. Doping with Cobalt corresponds to applying chemical pressure. Accordingly, the Néel-temperature is increased to T_N =1.7 K in the pure system YbCo₂Si₂, confirming a decrease of the hybridization between conduction electrons and Yb³⁺ 4f-spins. The anisotropies of the ESR g-factor and the ESR linewidth Δ B for three different frequencies (L, X, Q-band) and in a temperature range from T ≈ 1.5 K to ≈ 10 K are presented and discussed here. A significant decrease of the anisotropy from x=0 to 1 is observed.