Heat transport of electron-doped Cobaltates

Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermion-spin theory. It is shown that the temperature dependent thermal conductivity is characterized by the low temperature peak located at a finite temperature. The thermal conductivity increases monotonously with increasing temperature at low temperatures T $<$ 0.1$J$, and then decreases with increasing temperature for higher temperatures T $>$ 0.1$J$, in qualitative agreement with experimental result observed from Na${}_x$CoO${}_2$ .