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Dimer and Néel order-parameter fluctuations in the spin-fluid phase of the s=1/2 spin chain with first and second neighbor couplings

Yongmin Yu·Gerhard Müller·V. S. Viswanath
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Abstract

The dynamical properties at T=0 of the one-dimensional (1D) s=1/2 nearest-neighbor (nn) XXZ model with an additional isotropic next-nearest-neighbor (nnn) coupling are investigated by means of the recursion method in combination with techniques of continued-fraction analysis. The focus is on the dynamic structure factors S_{zz}(q,ω) and S_{DD}(q,ω), which describe (for q=π) the fluctuations of the Néel and dimer order parameters, respectively. We calculate (via weak-coupling continued-fraction analysis) the dependence on the exchange constants of the infrared exponent, the renormalized bandwidth of spinon excitations, and the spectral-weight distribution in S_{zz}(π,ω) and S_{DD}(π,ω), all in the spin-fluid phase, which is realized for planar $nn$ anisotropy and sufficiently weak nnn coupling. For some parameter values we find a discrete branch of excitations above the spinon continuum. They contribute to S_{zz}(q,ω) but not to S_{DD}(q,ω).

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Yongmin Yu, Gerhard Müller, V. S. Viswanath. 1996-04-11. Dimer and Néel order-parameter fluctuations in the spin-fluid phase of the s=1/2 spin chain with first and second neighbor couplings. https://doi.org/10.1103/physrevb.54.9242

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