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Bound spinons in an antiferromagnetic S=1/2 chain with a staggered field

M. Kenzelmann·Y. Chen·C. Broholm·D. H. Reich·Y. Qiu
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Abstract

Inelastic neutron scattering was used to measure the magnetic field dependence of spin excitations in the antiferromagnetic S=1/2 chain CuCl_2 2(dimethylsulfoxide) (CDC) in the presence of uniform and staggered fields. Dispersive bound states emerge from a zero-field two-spinon continuum with different finite energy minima at wave numbers q=pi and q_i approx pi (1-2 ). The ratios of the field dependent excitation energies are in excellent agreement with predictions for breather and soliton solutions to the quantum sine-Gordon model, the proposed low-energy theory for S=1/2 chains in a staggered field. The data are also consistent with the predicted soliton and n=1,2 breather polarizations and scattering cross sections.

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M. Kenzelmann, Y. Chen, C. Broholm, D. H. Reich, Y. Qiu. 2004-02-24. Bound spinons in an antiferromagnetic S=1/2 chain with a staggered field. https://doi.org/10.1103/physrevlett.93.017204

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