Abstract
We study the binding of a holon and a spinon in the one-dimensional anisotropic model using a Bethe-Salpeter equation approach, exact diagonalization, and density matrix renormalization group methods on chains of up to 128 sites. We find that holon-spinon binding changes dramatically as a function of anisotropy parameter : it evolves from an exactly deducible impuritylike result in the Ising limit to an exponentially shallow bound state near the isotropic case. A remarkable agreement between the theory and numerical results suggests that such a change is controlled by the corresponding evolution of the spinon energy spectrum.
- Received 29 January 2007
DOI:https://doi.org/10.1103/PhysRevLett.98.266401
©2007 American Physical Society