Abstract
We investigate the electronic properties of a two-leg ladder model by taking into account the combined effects of long-range correlations along the longitudinal direction and short-range correlations in the transverse direction. The strength of both correlations is measured by the correlation exponent and by the interchain hopping integral , respectively. Within the framework of the tight-binding Hamiltonian, we calculate the density of states, the localization length, and the participation ratio. Our results indicate that the short-range correlations will induce a crossover from localization to delocalization in the side energy bands of the two-leg ladder with finite system size by increasing , and the long-range correlations will lead to a localization-delocalization transition by increasing , while the electronic states in the central region are still localized. The two side energy bands will present truly delocalized states for in the thermodynamic limit. Furthermore, the two-leg ladders of different types of short-range correlations will show quite different localization properties. The system with the pair correlations, where the on-site energies at the same longitudinal positions of two chains always have opposite values, exhibits a larger localization length in the side energy bands.
- Received 29 October 2010
DOI:https://doi.org/10.1103/PhysRevB.83.245108
©2011 American Physical Society