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Regular version of the site

Article

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

Poboiko I., Feigelman M.

We study a one-dimensional anisotropic XXZ spin-1/2 model with ferromagnetic sign of the coupling and z−z exchange constant Jz=ΔJ, where Δ<1, and J is the coupling within the XY spin plane. We calculate the damping of low-energy excitations with ω≪T due to their scattering from thermal excitation bath with temperature T≪J, taking into account nonzero curvature of the excitation spectrum, ε(q)=uq+δε(q). We calculate also longitudinal spin-spin correlation function ⟨Sz(x,t)Sz(0,0)⟩ at x≈ut and find the shape of the spreading “wave packet”.