Springer LINK: The European Physical Journal B - Abstract Volume 3 Issue 4 (1998) pp 427-435

The European Physical Journal B

ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)

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Abstract Volume 3 Issue 4 (1998) pp 427-435

Charge correlations in the weakly doped $\mathsf{t{-}J}$ model calculated by projection technique

M. Vojta (a), K.W. Becker

Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany

Received: 10 July 1997 / Revised: 19 March 1998 / Accepted: 3 April 1998

Abstract: We study frequency- and wave-vector dependent charge correlations in weakly doped antiferromagnets using Mori-Zwanzig projection technique. The system is described by the two-dimensional t-J model. The ground state is expressed within a cumulant formalism which has been successfully applied to study magnetic properties of the weakly doped system. Within this approach the ground state contains independent spin-bag quasiparticles (magnetic polarons). We present results for the charge-density response function and for the optical conductivity at zero temperature for different values of t/J. They agree well with numerical results calculated by exact diagonalization techniques. The density response function for intermediate and large momenta shows a broad continuum on energy scales of order of several t whereas the optical conductivity for $\omega \gt 0$ is dominated by low energy excitations (at 1.5-2J). We show that these weak-doping properties can be well understood by transitions between excited states of spin-bag quasiparticles.

PACS. 74.25.Fy Transport properties (electric and thermal conductivity thermoelectric effects, etc.) - 75.10.Jm Quantized spin models - 75.50.Ee Antiferromagnetics

(a) email: vojta@theory.phy.tu-dresden.de

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