Year: 1996
Type: article
Abstract: We present an exact-diagonalization study of the frequency- and wave-vector-dependent conductivity $\ensuremath{\sigma}(\mathrm{q}, \ensuremath{\omega})$ in small clusters in the two-dimensional $t\ensuremath{-}J$ model. Unlike the related dynamical density correlation function, $\ensuremath{\sigma}(\mathrm{q}=0, \ensuremath{\omega})$ in the underdoped regime has the exchange constant $J$ as its characteristic energy scale and is dominated by a resonancelike excitation with frequency $\ensuremath{\sim}1.7J$. We interpret this as transition to a $p$-like excited state of a spin-bag-type quasiparticle (or, alternatively, a tightly bound spinon-holon pair) and show that a simple calculation based on the string picture explains the numerical results semiquantitatively. For doping levels $>~25%t$ remains the only energy scale of $\ensuremath{\sigma}(\mathrm{q}=0, \ensuremath{\omega})$.
Authors: R. Eder, P. Wróbel, Y. Ohta
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1986659333