Spectral function of one hole in several one-dimensional spin arrangements

摘要

The spectral function of one hole in different magnetic states of the one-dimensional t-J model including three-site term and frustration J' is studied. In the strong-coupling limit J-->0 (corresponding to U-->infinity of the Hubbard model) a set of eigenoperators of the Liouvillian is found which allows us to derive an exact expression for the one-particle Green's function that is also applicable at finite temperature and in an arbitrary magnetic state. The spinon dispersion of the pure t-J model with the ground state of the Heisenberg model can be obtained by treating the corrections due to a small exchange term by means of the projection method. The spectral function for the special frustration J' = J/2 with the Majumdar-Ghosh wave function is discussed in detail. Besides the projection method, a variational ansatz with the set of eigenoperators of the t term is used. We find a symmetric spinon dispersion around the momentum k = pi/(2a) and a strong damping of the holon branch Below the continuum a bound state is obtained with finite spectral weight and a very small separation from the continuum. Furthermore, the spectral function of the ideal paramagnetic case at a temperature k(B)T much greater thanJ is discussed. [References: 26]