Theoretical study of thermoelectric and Hall effects in the layered cobalt oxides, [formula omitted

Abstract

We examine the response of the transport properties to the magnetic field and temperature gradient in the Hubbard model on the kagomé lattice within the limit of U → ∞ , using the “retraceable-path” approximation. The layered cobalt oxides, Na x CoO 2 , involve the triangular lattice of the cobalt ions. However, the electron trajectory makes up the kagomé lattice due to the orbital degeneracy of t 2 g states. It is shown that this kagomé lattice hidden in the CoO 2 layer exhibits the anomalous high-temperature Hall effect recently observed by Wang et al.