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Spin correlation functions in random-exchange s=1/2 XXZ chains

Heinrich Röder·Joachim Stolze·Richard N. Silver·Gerhard Müller
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Abstract

The decay of (disorder-averaged) static spin correlation functions at T=0 for the one-dimensional spin-1/2 XXZ antiferromagnet with uniform longitudinal coupling $JΔ$ and random transverse coupling $Jλ_i$ is investigated by numerical calculations for ensembles of finite chains. At $Δ=0$ (XX model) the calculation is based on the Jordan-Wigner mapping to free lattice fermions for chains with up to N=100 sites. At $Δ\neq 0$ Lanczos diagonalizations are carried out for chains with up to N=22 sites. The longitudinal correlation function $ $ is found to exhibit a power-law decay with an exponent that varies with $Δ$ and, for nonzero $Δ$, also with the width of the $λ_i$-distribution. The results for the transverse correlation function $ $ show a crossover from power-law decay to exponential decay as the exchange disorder is turned on.

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Heinrich Röder, Joachim Stolze, Richard N. Silver, Gerhard Müller. 1995-11-16. Spin correlation functions in random-exchange s=1/2 XXZ chains. https://doi.org/10.1063/1.361687

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