Minute zero–magnon component and predominant multi-magnon one in photoemission spectra of the two-dimensional half-filled Hubbard system

Abstract

We show how the coherent and the incoherent components contribute to the one-body Green's function for the two-dimensional half-filled Hubbard model. By adding a site-diagonal staggered potential, a magnon gap artificially opens and, as a result, the zero–magnon coherent component is clearly separated from the multi-magnon incoherent one. We show that the incoherent component predominates the spectrum of the usual Hubbard system, while the coherent component makes only a minute contribution.