Heat Transport of Electron-Doped Cobaltates

Within the t-J model, the heat transport of electron-dopedcobaltates is studied based on the fermion-spin theory. It isshown that the temperature-dependent thermal conductivity ischaracterized by the low-temperature peak located at a finitetemperature. The thermal conductivity increases monotonously withincreasing temperature at low-temperatures T<0.1J, and thendecreases with increasing temperature for higher temperatures T>0.1J, in qualitative agreement with experimental result observed from Na_xCoO₂.