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Lineshape predictions via Bethe ansatz for the one-dimensional spin-1/2 Heisenberg antiferromagnet in a magnetic field

Michael Karbach·Gerhard Muller
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Abstract

The spin fluctuations parallel to the external magnetic field in the ground state of the one-dimensional (1D) s=1/2 Heisenberg antiferromagnet are dominated by a two-parameter set of collective excitations. In a cyclic chain of N sites and magnetization 0 \infty, these collective excitations form a continuum in (q,ω)-space with an incommensurate soft mode. Their matrix elements in the dynamic spin structure factor S_{zz}(q,ω) are calculated directly from the Bethe wave functions for finite N. The resulting lineshape predictions for N -> \infty complement the exact results previously derived via algebraic analysis for the exact 2-spinon part of S_{zz}(q,ω) in the zero-field limit. They are directly relevant for the interpretation of neutron scattering data measured in nonzero field on quasi-1D antiferromagnetic compounds.

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Michael Karbach, Gerhard Muller. 2000-05-10. Lineshape predictions via Bethe ansatz for the one-dimensional spin-1/2 Heisenberg antiferromagnet in a magnetic field. https://doi.org/10.1103/physrevb.62.14871

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