Quasiparticle band in the frustrated t-t'-J model

We investigate the influence of frustration on the quasiparticle dispersion in the t-J and t-t'-J models using the linear spin-wave theory and self-consistent Born approximation. The next-neighbor antiferromagnetic interactions, simulating the effect of doping within CuO2 planes of high-T-c superconductors, lead to a drastic reduction of the quasiparticle bandwidth with the increasing frustration in a wide range of t, t', and J parameters. The low-energy quasiparticle band (with the width only similar to 0.3 eV) obtained for the realistic values of parameters and a very weak quasiparticle state at the (0,0) point in the Brillouin zone agree quite well with the flat band observed at the Fermi level in the angle-resolved photoemission experiments for Bi2Sr2CaCu2O8+delta.