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Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Quantum Impurities, Kondo Physics

TT 30.12: Talk

Tuesday, March 12, 2013, 12:30–12:45, H21

Possible non-Fermi liquid behavior in transport through Co doped Au chains — •Andreas Weichselbaum1, Solange Di Napoli2, Pablo Roura-Bas2, Armando A. Aligia3, Yuriy Mokrousov4, and Stefan Blügel41Ludwig-Maximilians-Universität, München, Germany — 2Departamento de Física de la Materia Condensada, Buenos Aires, Argentina — 3Centro Atómico Bariloche and Instituto Balseiro, Bariloche, Argentina — 4Institut für Festkörperforschung, Forschungszentrum Jülich, Germany

We calculate the conductance as a function of temperature G(T) through monoatomic Au chains, which contain one Co atom as a magnetic impurity and are connected to two conducting leads with a 4-fold symmetry axis. Using the information derived from ab initio calculations, we construct an effective model Hamiltonian Heff that hybridizes a 3d7 quadruplet at the Co site with two 3d8 triplets through the hopping of 5dxz and 5dyz electrons of Au. The quadruplet is split by a term D Sz,Co2 due to spin-orbit coupling at the Co site. Solving Heff with the numerical renormalization group (NRG), we find at low temperatures G(T) = abT together with a ground state impurity entropy of ln(2)/2, a behavior similar to the two-channel Kondo model. Stretching the chain one expects a quantum phase transition to a non-Kondo phase, with the physics of the underscreened Kondo model at the quantum critical point.

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