arXiv:cond-mat/0605091 · Physical Review B
Competitive density waves in quasi-one-dimensional electron systems
Samuele Bissola, Alberto Parola
Abstract
We investigate the nature of the ground state of the one-dimensional $t\text{\ensuremath{-}}J$ model coupled to adiabatic phonons by use of the Lanczos technique at quarter filling. Due to the interplay between electron-electron and electron-phonon interactions, the model undergoes instabilities toward the formation of lattice and charge modulations. Moderate on-site and intrasite electron-phonon couplings lead to a competition of different spin-Peierls and dimerized states. In the former case two electrons belong to the unit cell and we expect a paramagnetic band insulator state, while lattice dimerization leads to a Mott insulating state with (quasi) long range antiferromagnetic order. The zero temperature phase diagram is obtained as a function of intrasite and intersite electron-phonon couplings, analytically in the $J\ensuremath{\rightarrow}0$ limit and numerically at finite $J∕t$.