Numerical Studies of the two-leg Hubbard ladder

Abstract

The Hubbard model on a two-leg ladder structure has been studied by a combination of series expansions at T=0 and the density-matrix renormalization group. We report results for the ground state energy $E_0$ and spin-gap ${\Delta }_s$ at half-filling, as well as dispersion curves for one and two-hole excitations. For small $U$ both $E_0$ and ${\Delta }_s$ show a dramatic drop near $t/t_{\perp }\sim 0.5$, which becomes more gradual for larger $U$. This represents a crossover from a "band insulator" phase to a strongly correlated spin liquid. The lowest-lying two-hole state rapidly becomes strongly bound as $t/t_{\perp }$ increases, indicating the possibility that phase separation may occur. The various features are collected in a "phase diagram" for the model.

10 figures, revtex

References in corpus (2)

• Phase separation in t-J ladders
• Studies of the t-J two-leg ladder via series expansions

Cited by in corpus (12)

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• Two-loop renormalization-group theory for the quasi-one-dimensional Hubbard model at half filling
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• Entanglement studies of interacting fermionic models
• Terminable Transitions in a Topological Fermionic Ladder