Weakly correlated triangular lattice metal HxCoO2 with x≈0.3

Abstract

A new type of the triangular lattice system, HxCoO2 (x≈0.3), is synthesized through chemical extraction of Na from Na 0.3CoO2 with H2SO4. The structure is modelled by two oxygen layers with a prismatic oxygen environment and a symmetric linear H-O bond on the basis of x-ray powder diffraction and magic-angle spinning NMR analyses. Measurements of the electrical resistivity, thermoelectric power and magnetic susceptibility suggest a weakly correlated metallic state with the enhancement of effective mass. Transport anomalies, accompanied with the rapid decrease of thermoelectric power, are observed at about 10K. © IOP Publishing Ltd.