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

TL;DR

This paper extends the spectral function analysis in the generalized t-J model to include quasiparticle weights, comparing different computational approaches and discussing effects of longer-range hopping and three-site terms.

Contribution

It introduces an extended SCBA method for spectral functions and quasiparticle weights, comparing it with other approaches and exact diagonalization results.

Findings

SCBA results align well with exact diagonalization data

Longer-range hopping influences quasiparticle properties

Three-site terms affect spectral function characteristics

Abstract

We extend to the spectral function an approach which allowed us to calculate the quasiparticle weight for destruction of a real electron Z_c sigma (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 Z_c sigma (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.