Single-hole properties of the t-J model on the honeycomb lattice

Motivated by the possible charge ordering in the recently discovered superconductor NaxCoO2 yH2O, which at filling x=1/3 would correspond to a half-filled honeycomb lattice, we investigate the single-hole dynamics of the t-J model on this lattice. Using exact diagonalization, series expansion, and the self-consistent Born approximation, we calculate the quasiparticle dispersion, bandwidth, and residues and compare our findings to the well-established results for the square lattice. Given the similarities between both lattices, it is not surprising that we find qualitatively similar features for the honeycomb lattice, namely, an almost flat band along the edge of the magnetic Brillouin zone and well-defined hole pockets around the corners. However, we report a considerable disagreement between the three methods used concerning the bandwidth and discuss possible origins of this discrepancy.