FERMI-SURFACE AND DYNAMICS OF THE T-J MODEL AT MODERATE DOPING

The 2D t-J model is studied with exact-diagonalization techniques applied to clusters of sixteen to twenty sites with various hole doping levels. Already for two holes (greater-than-or-equal-to 10% doping), a large electronic Fermi surface, compatible with Luttinger's theorem, is observed. The full single-particle Green's function is examined, and is shown to exhibit quasiparticlelike behavior, with dispersion consistent with the band structure of the noninteracting limit, and bandwidth scaling approximately as J for J smaller than t.