Quantum Effects in the Dynamics of the One-Dimensional Planar Antiferromagnet

Abstract

In a recent publication /1/ we found that the T=o dynamics of the 1D s=1/2 Heisenberg antiferromagnet (HB AF) with nearest-neighbor exchange interaction J is almost completely dominated by a particular continuum of excitations (called spin-wave continuum, SWC) bounded by the dispersion branches ε₁(q) = (πJ/2)sinq and ε₂(q)=πJsin(q/2). It differs markedly from the classical 1D HB AF where the spectral weight is concentrated on a single branch of spin-waves. The result for the structure function ${S_{\mu \mu }}\left( {q,\omega } \right) \equiv {\left\langle {S_l^uS_l^u} \right\rangle _{q,\omega }}$ which is a special case of Eq.(6), is in good agreement with low-T neutron scattering data on CPC /2/ concerning excitation energies, lineshapes and integrated intensity.