From Gapped Excitons to Gapless Triplons in One Dimension

Abstract

Often, exotic phases appear in the phase diagrams between conventional phases. Their elementary excitations are of particular interest. Here, we consider the example of the ionic Hubbard model in one dimension. This model is a band insulator (BI) for weak interaction and a Mott insulator (MI) for strong interaction. Inbetween, a spontaneously dimerized insulator (SDI) occurs which is governed by energetically low-lying charge and spin degrees of freedom. Applying a systematically controlled version of the continuous unitary transformations (CUTs) we are able to determine the dispersions of the elementary charge and spin excitations and of their most relevant bound states on equal footing. The key idea is to start from an externally dimerized system using the relative weak interdimer coupling as small expansion parameter which finally is set to unity to recover the original model.

18 pages, 10 figures

References in corpus (8)

• Effective spin model for the spin-liquid phase of the Hubbard model on the triangular lattice
• Phase diagram of the one-dimensional half-filled extended Hubbard model
• Quantum Monte Carlo Study of an Interaction-Driven Band Insulator to Metal Transition
• Electronic phase transitions in the half-filled ionic Hubbard model
• Effective models for gapped phases of strongly correlated quantum lattice models
• DMRG Study of Critical Behavior of the Spin-1/2 Alternating Heisenberg Chain
• Dispersive Excitations in the One-Dimensional Ionic Hubbard Model
• Excitation Spectrum of One-dimensional Extended Ionic Hubbard Model

Cited by in corpus (2)

• Probing the bond order wave phase transitions of the ionic Hubbard model by superlattice modulation spectroscopy
• Antiferromagnetic Chern insulator in centrosymmetric systems