Dominance of the excitation continuum in the longitudinal spectrum of weakly coupled Heisenberg S=1/2 chains |
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Authors: | Zheludev A Kakurai K Masuda T Uchinokura K Nakajima K |
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Institution: | Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA. zheludevai@ornl.gov |
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Abstract: | A low-field spin-flop transition in the quasi-one-dimensional antiferromagnet BaCu2Si2O7 is exploited to study the polarization dependence of low-energy magnetic excitations. The measured longitudinal spectrum is best described as a single broad continuum, with no sharp "longitudinal mode," in apparent contradiction with the commonly used chain-mean-field and random phase approximation (MF/RPA) theories. The observed behavior is also quite different than that previously seen in the related KCuF3 material, presumably due to a large difference in the relative strength of interchain interactions. The results highlight the limitations of the chain-MF/RPA approach. |
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