Dynamic correlations of antiferromagnetic spin-1/2 XXZ chains at arbitrary temperature from complete diagonalization

Klaus Fabricius; Ute Löw; Joachim Stolze

doi:10.1103/PhysRevB.55.5833

paper

Dynamic correlations of antiferromagnetic spin-1/2 XXZ chains at arbitrary temperature from complete diagonalization

arXiv:cond-mat/9611077 · doi:10.1103/PhysRevB.55.5833

Abstract

All eigenstates and eigenvalues are determined for the spin- 1/2 $X X Z$ chain $H = 2 J \sum_{i} (S_{i}^{x} S_{i + 1}^{x} + S_{i}^{y} S_{i + 1}^{y} + Δ S_{i}^{z} S_{i + 1}^{z})$ for rings with up to N=16 spins, for anisotropies $Δ = 0, cos (0.3 π)$ , and 1. The dynamic spin pair correlations $< S_{l + n}^{μ} (t) S_{l}^{μ} >, (μ = x, z)$ , the dynamic structure factors $S^{μ} (q, ω)$ , and the intermediate structure factors $I^{μ} (q, t)$ are calculated for arbitrary temperature T. It is found, that for all T, $S^{z} (q, ω)$ is mainly concentrated on the region $∣ ω ∣ < ε_{2} (q)$ , where $ε_{2} (q)$ is the upper boundary of the two-spinon continuum, although excited states corresponding to a much broader frequency spectrum contribute. This is also true for the Haldane-Shastry model and the frustrated Heisenberg model. The intermediate structure factors $I^{μ} (q, t)$ for $Δ \neq = 0$ show exponential decay for high T and large q. Within the accessible time range, the time-dependent spin correlation functions do not display the long-time signatures of spin diffusion.

30 pages, REVTEX, 21 figures, to appear in Physical Review B

Dynamic correlations of antiferromagnetic spin-1/2 XXZ chains at arbitrary temperature from complete diagonalization

Abstract

References in corpus (7)

Cited by in corpus (55)