Metal-insulator transition in one-dimensional Hubbard superlattices

Abstract

We study the Metal-Insulator transition in one-dimensional Hubbard superlattices (SL's), modelled by a repeated pattern of repulsive (i.e., positive on-site coupling) and free sites. The evolution of the local moment and of the charge gap (calculated from Lanczos diagonalization of chains up to 18 sites), together with a strong coupling analysis, show that the electron density at which the system is insulating increases with the size of the free layer, relative to the repulsive one. In the insulating state, the mechanism of interaction between fermions separated by a free layer is the analog of superexchange, and the charge gap display universal features. mit.tex -PACS: 71.30.+h 71.27.+a,

Modulation of charge-density waves by superlattice structures

“…[16][17][18] Also, the density at which the system is a Mott insulator I is shifted from half filling to a value which depends on the aspect ratio. 19 These findings on a discrete lattice have been confirmed by an extension of the above model to a superlattice made up of Luttinger liquids ͑LL͒.…”

Multiperiodic magnetic structures in Hubbard superlattices

“…14 In the region between ↑↓ and I , the repulsive layer is preferentially filled as the overall density is increased, causing a steep rise ͑drop͒ in the local moment at the repulsive ͑free͒ sites. As Fig.…”

“…13 In addition, spin-density-wave ͑SDW͒ quasiorder can be wiped out as a result of frustration, and the SL structure also induces a shift in the density I at which a Mott-Hubbard insulating phase sets in. 14 Further, by examining the Luttinger liquid version of the model, 15 one finds that these superlattices provide the means to realize gapless insulating phases. 16 Previous studies of the discrete version of the model 12-14 resorted to Lanczos diagonalization, which sets limits on the system sizes used; for instance, a 24-site lattice size could only be considered for the low-and high-density regimes ( ϭ1/6 and ϭ11/6).…”

“…With this in mind, here we investigate the magnetic properties of a one-dimensional superlattice ͑SL͒ model [12][13][14] in which electronic correlations are incorporated and treated nonperturbatively. The model consists of a periodic arrangement of L U sites ͑''layers''͒ in which the on-site coupling is repulsive, followed by L 0 free ͑i.e., Uϭ0) sites.…”

Electric field induced localization phenomena in a ladder network with superlattice configuration: Effect of backbone environment

“…1), in presence of an external electric field. Incidentally, many interesting and novel features of electronic properties have already been examined in different types of 1D superlattice chains, [19][20][21][22][23] which are considered as the equivalent representation of periodic structures of different metallic layers. [24][25][26] The motivation of the present study is two-fold.…”