UNSPECIFIED (2001) Excitons in one-dimensional Mott insulators. PHYSICAL REVIEW B, 6412 (12). -. ISSN 0163-1829

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Abstract

We employ dynamical density-matrix renormalization-group (DDMRG) and field-theory methods to determine the frequency-dependent optical conductivity in one-dimensional extended. half-filled Hubbard models. The field-theory approach is applicable to the regime of "small" Mott gaps which is the most difficult to access by DDMRG. For very large Mott gaps the DDMRG recovers analytical results obtained previously by means of strong-coupling techniques. We focus on exciton formation at energies below the onset of the absorption continuum. As a consequence of spin-charge separation, these Mott-Hubbard excitons are bound states of spinless, charged excitations ("holon-antiholon" pairs). We also determine exciton binding energies and sizes. In contrast to simple band insulators, we observe that excitons exist in the Mott-insulating phase only for a sufficiently strong intersite Coulomb repulsion. Furthermore, our results show that the exciton binding energy and size are not related in a simple way to the strength of the Coulomb interaction.

Item Type:	Journal Article
Subjects:	Q Science > QC Physics
Journal or Publication Title:	PHYSICAL REVIEW B
Publisher:	AMERICAN PHYSICAL SOC
ISSN:	0163-1829
Date:	15 September 2001
Volume:	6412
Number:	12
Number of Pages:	15
Page Range:	-
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/11723

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