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arXiv:1608.05937 · Physical review. B./Physical review. B

Spin correlation functions and decay of quasiparticles in XXZ spin chain at T>0

Igor Poboiko, M. V. Feigel’man

Published Nov 14, 2016• 3 citations
arXivHTMLPDF

Abstract

We study a one-dimensional anisotropic $XXZ \text{spin-}\frac{1}{2}$ model with ferromagnetic sign of the coupling and $z\text{\ensuremath{-}}z$ exchange constant ${J}_{z}=\mathrm{\ensuremath{\Delta}}J$, where $\mathrm{\ensuremath{\Delta}}<1$, and $J$ is the coupling within the $XY$ spin plane. We calculate the damping of low-energy excitations with $\ensuremath{\omega}\ensuremath{\ll}T$ due to their scattering from thermal excitation bath with temperature $T\ensuremath{\ll}J$, taking into account nonzero curvature of the excitation spectrum, $\ensuremath{\epsilon}(q)=uq+\ensuremath{\delta}\ensuremath{\epsilon}(q)$. We calculate also longitudinal spin-spin correlation function $\ensuremath{\langle}{S}^{z}(x,t){S}^{z}(0,0)\ensuremath{\rangle}$ at $x\ensuremath{\approx}ut$ and find the shape of the spreading ``wave packet''.

DOI
10.1103/physrevb.94.195420

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