Multiorbital Kondo physics of Co in Cu hosts

Brigitte Surer, Matthias Troyer, Philipp Werner, Tim O. Wehling, Andreas M. Läuchli, Aljoscha Wilhelm, and Alexander I. Lichtenstein
Phys. Rev. B 85, 085114 – Published 21 February 2012

Abstract

We investigate the electronic structure of cobalt atoms on a copper surface and in a copper host by combining density-functional calculations with a numerically exact continuous-time quantum Monte Carlo treatment of the five-orbital impurity problem. In both cases we find low energy resonances in the density of states of all five Co d orbitals. The corresponding self-energies indicate the formation of a Fermi liquid state at low temperatures. Our calculations yield the characteristic energy scale—the Kondo temperature—for both systems in good agreement with experiments. We quantify the charge fluctuations in both geometries and suggest that Co in Cu must be described by an Anderson impurity model rather than by a model assuming frozen impurity valency at low energies. We show that fluctuations of the orbital degrees of freedom are crucial for explaining the Kondo temperatures obtained in our calculations and measured in experiments.

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  • Received 19 July 2011

DOI:https://doi.org/10.1103/PhysRevB.85.085114

©2012 American Physical Society

Authors & Affiliations

Brigitte Surer, Matthias Troyer, and Philipp Werner

  • Theoretische Physik, ETH Zurich, CH-8093 Zurich, Switzerland

Tim O. Wehling

  • Institut für Theoretische Physik, Universität Bremen, Otto-Hahn-Allee 1, D-28359 Bremen, Germany and Bremen Center for Computational Materials Science, Am Fallturm 1a, D-28359 Bremen, Germany

Andreas M. Läuchli

  • Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany and Institut für Theoretische Physik, Universität Innsbruck, Technikerstrasse 25/2, A-6020 Innsbruck, Austria

Aljoscha Wilhelm and Alexander I. Lichtenstein

  • Institut für Theoretische Physik, Universität Hamburg, D-20355 Hamburg, Germany

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Issue

Vol. 85, Iss. 8 — 15 February 2012

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