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Magnetic Excitations in the S=1/2 Alternating Chain Compound (VO)_2P_2O_7

A. W. Garrett·S. E. Nagler·D. A. Tennant·B. C. Sales·T. Barnes
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Abstract

Magnetic excitations in an array of (VO)_2P_2O_7 single crystals have been measured using inelastic neutron scattering. Until now, (VO)_2P_2O_7 has been thought of as a two-leg antiferromagnetic Heisenberg spin ladder with chains running in the a-direction. The present results show unequivocally that (VO)_2P_2O_7 is best described as an alternating spin-chain directed along the crystallographic b-direction. In addition to the expected magnon with magnetic zone-center energy gap Δ= 3.1 meV, a second excitation is observed at an energy just below 2Δ. The higher mode may be a triplet two-magnon bound state.

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A. W. Garrett, S. E. Nagler, D. A. Tennant, B. C. Sales, T. Barnes. 1997-04-10. Magnetic Excitations in the S=1/2 Alternating Chain Compound (VO)_2P_2O_7. https://doi.org/10.1103/physrevlett.79.745

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