Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 43: Correlated Electrons: Heavy Fermions 2

TT 43.4: Vortrag

Donnerstag, 26. März 2009, 16:30–16:45, HSZ 301

Non-Fermi-Liquid Behaviour in CaCu₃Ru₄O₁₂ Studied by Nuclear Magnetic Resonance — •Wolfgang Krätschmer¹, Heiko Dekinger¹, Norbert Büttgen¹, Alois Loidl¹, Axel Günther¹, Alexander Krimmel¹, and Ernst-Wilhelm Scheidt² — ¹Experimentalphysik 5, Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, 86135 Augsburg, Deutschland — ²CPM, Universität Augsburg, 86135 Augsburg, Deutschland

We present a detailed study of the electronic properties of CaCu₃Ru₄O₁₂ which has perovskite structure and shows strong electron correlations. Beside magnetic susceptibility, transport and specific heat data, we focus on NMR and NQR measurements at the copper and ruthenium sites in this compound [Krimmel et al., PRB 78, 165126 (2008)]. CaCu₃Ru₄O₁₂ is a metallic system showing non-Fermi-liquid behaviour below 2K which becomes manifest in a logarithmic increase of the specific heat C_p/T∝ −ln(T) and in an NQR spin-lattice relaxation rate 1/T₁ (T) that deviates from the Korringa law at the copper site only. Static NMR measurements were conducted to extract electric field gradients for the correction of the low-temperature specific heat data for nuclear contributions. Nuclear contributions turned out to be not sufficient to account for the Schottky-anomaly. Further investigation of the spin-lattice relaxation at the ruthenium site reveals a clearly different behaviour in comparison to the copper site and reflects the local character of the strong electron correlations.