Spectral function and quasiparticle weight in the generalized t–J model

Abstract

We extend to the spectral function an approach which allowed us to calculate the quasiparticle weight for destruction of a real electron Zcσ(k) (in contrast to that of creation of a spinless holon Z h (k)) in a generalized t − J model, using the self-consistent Born approximation (SCBA). We compare our results with those obtained using the alternative approach of Sushkov et al., which also uses the SCBA. The results for Zcσ(k) are also compared with results obtained using the string picture and with exact diagonalizations of a 32-site square cluster. While on a qualitative level, all results look similar, our SCBA approach seems to compare better with the ED one. The effect of hopping beyond nearest neighbors, and that of the three-site term are discussed.

Spectral Properties of CuO2 Planes in a Cluster Perturbation Approach

“…A solution to this shortcoming of the t-J model has been suggested, by introducing longer-range hopping and interaction terms. In fact, a mapping of the three-band Hubbard model into a generalized t-J model has been recently proposed 31 , which is consistent with results of the self-consistent Born approximation calculations and experimental data 32,30,33 . In particular, these latter results exhibit a dispersion in excellent agreement with our calculations of Fig.…”

Angle-resolved Cu and O photoemission intensities inCuO2planes

“…Eqs. (8) and (6) 35 ) . Defined in this way, Zhang-Rice singlets centered in nearest-neighbor Cu orbitals are non orthogonal 45 .…”

“…This equation, together with Eqs. (6) to (8) allow to calculate the Cu and O photoemission spectra of the threeband Hubbard model H 3b from the eigenstates of the corresponding generalized t − J model H GtJ . For the sake of clarity, and in absence of a more detailed knowledge about the experimental situation, we neglect effects of interference and the dependence on the polarization of the incident radiation and direction of the photoemitted electron.…”

“…However, as we show below, there is a simple analytical relation between the O contribution, generally the most important, and the quasiparticle weight of H GtJ for one added hole. The latter quantity has been calculated accurately with the SCBA 6,8,15 and compared with results of other analytical and numerical methods 8 .…”

“…More recently the photoemission intensities have been discussed [5][6][7][8]10,15 and compared with previous results in the t − J model [12][13][14] . In particular Lema and one of us 6,8 and Sushkov et al 15 , have developed two different methods to calculate the quasiparticle weight in the generalized t − J or one-band Hubbard models in the strong coupling limit, using the self-consistent Born approximation (SCBA). The results of both methods, an analytical approach based on the "string picture" 13 , and exact diagonalization of a 32-site cluster 7 were compared recently 8 .…”