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

TL;DR

This study explores the single-hole behavior in the t-J model on a honeycomb lattice, revealing similarities to the square lattice but also notable methodological discrepancies in bandwidth predictions.

Contribution

It provides the first detailed analysis of single-hole properties on the honeycomb lattice using multiple computational methods, highlighting both qualitative similarities and quantitative disagreements.

Findings

Qualitative similarity to square lattice features

Presence of flat bands and hole pockets

Discrepancies in bandwidth estimates between methods

Abstract

Motivated by the possible charge ordering in the recently discovered superconductor Na_xCoO_2 yH_2O, 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 quasi-particle dispersion, bandwidth and residues and compare our findings with 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.