Hole spectral functions in lightly doped quantum antiferromagnets
  We study the hole and magnon spectral functions as a function of hole doping in the two-dimensional (2D) t-J and t-t'-t"-J models working within the limits of the spin-wave theory, by linearizing the hole-spin-deviation interaction and by adapting the non-crossing approximation (NCA). We find that the staggered magnetization decreases rather rapidly with doping and it goes to zero at a few percent of hole concentration in both t-J and the t-t'-t"-J model. We find that with doping, the residue of the quasiparticle peak at G=(pi/2,pi/2) decreases rapidly with doping and the spectral function is in agreement with high resolution angle-resolved photo-emission spectroscopy (ARPES) studies of the copper-oxide superconductors. The observed large shift of the chemical potential inside the Mott gap is found to be a result of broadening of the quasiparticle peak. We find pockets centered at G, similar to those observed by quantum oscillation measurements, (i) with an elliptical shape with large eccentricity along the anti-nodal direction in the case of the t-J model, and (ii) with an almost circular shape in the case of the t-t'-t"-J model. We also find that the spectral intensity distribution in the doped antiferromagnet has a waterfall-like patten along the nodal direction of the Brillouin zone, a feature that is also seen in ARPES measurements. 
Satyaki Kar and Efstratios Manousakis
cond-mat.str-el