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Dominance of excitation continuum in the longitudinal spectrum of weakly coupled Heisenberg S=1/2 chains

A. Zheludev·K. Kakurai·T. Masuda·K. Uchinokura·K. Nakajima
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Abstract

A low-field spin flop transition in the quasi one-dimensional antiferromagnet \ba is exploited to study the polarization dependence of low-energy magnetic excitations. The measured longitudinal spectrum is best described as single broad continuum, with no sharp ``longitudinal mode'', in apparent contradiction with the commonly used chain-MF/RPA theories. The observed behavior is also quite different than that previously seen in the related \kcuf material, presumably due to a large difference in the relative strength of inter-chain interactions. The results highlight the limitations of the chain-MF/RPA approach.

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A. Zheludev, K. Kakurai, T. Masuda, K. Uchinokura, K. Nakajima. 2002-10-25. Dominance of excitation continuum in the longitudinal spectrum of weakly coupled Heisenberg S=1/2 chains. https://doi.org/10.1103/physrevlett.89.197205

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