From frustrated insulators to correlated anisotropic metals: charge-ordering and quantumcriticality in coupled chain systems

Abstract

By following the ideas of Emery and Noguera, a recent study revealed the dynamicsof the charge sector of a one-dimensional quarter-filled electronic system withextended Hubbard interactions to be that of an effective pseudospin transverse-fieldIsing model (TFIM) in the strong-coupling limit. With the twin motivations ofstudying the co-existing charge and spin order found in strongly correlated chainsystems and the effects of interchain couplings, we investigate the phase diagram ofcoupled effective (TFIM) systems. A bosonization and renormalization group(RG) analysis for a two-leg TFIM ladder yields a rich phase diagram showingWigner/Peierls charge order and Néel/dimer spin order. In a broad parameterregime, the orbital antiferromagnetic phase is found to be stable. An intermediategapless phase of finite width is found to lie in between two charge-ordered gappedphases. Kosterlitz–Thouless transitions are found to lead from the gapless phase toeither of the charge-ordered phases. A detailed analysis is also carried out for thedimensional crossover physics when many such pseudospin systems are coupled toone another. Importantly, the analysis reveals the key role of critical quantumfluctuations in driving the strong dispersion in the transverse directions, as well as aT = 0 deconfinement transition. Our work is potentially relevant for a unified description of aclass of strongly correlated, quarter-filled chain and ladder systems.