The origin of the temperature dependence of the magnetic susceptibility and the large thermoelectric power in metallic layered cobaltites

ORAL

Abstract

We perform detailed measurements of the thermoelectric power and the static magnetic susceptibility on metallic Na$_{x}$CoO${_2}$ and Ca$_{3}$Co$_{4}$O$_{9}$, as representatives of layered Co oxides with a triangular Co-lattice. We propose that the observed large thermoelectric power and the Curie-Weiss temperature dependence of the susceptibility have a common origin related to metallic character of these compounds. Thermoelectric power measurements are compared to Boltzmann transport theory calculations. The Curie-Weiss behaviour of the susceptibility is explained within the framework of the self-consistent renormalization theory for spin fluctuations proposed by Moriya for itinerant magnets. Our results clarify the apparent duality in the localised/itinerant behaviour of the electron spin in these systems and provide a unifying view on the physics of metallic layered cobaltites.

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Authors

  • Iv\'an Gonz\'alez

    Centro de Supercomputaci\'on de Galicia, Avda. de Vigo s/n, E-15705 Santiago de Compostela

  • Camilo X. Quintela

    Applied Physics Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain

  • Manuel Ba\~nobre-L\'opez

    Physical-Chemistry Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain

  • Francisco Rivadulla

    Physical Chemistry Dept. and Center for Research in Biological Chemistry and Molecular Materials, Univ. Santiago Compostela, Spain, Physical-Chemistry Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain, Departament of Physical Chemistry, University of Santiago de Compostela, Spain