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We use inelastic neutron scattering to probe the magnetic excitations in a single crystal sample of the proposed S=1/2 linear chain antiferromagnet Sr₂V₃O₉.  The primary excitations associated with the S=1/2 linear chain Heisenberg antiferromagnet are fractional quasiparticles known as spinons.  A spinon continuum with a bandwidth of approximately 22 meV is found to exist Sr₂V₃O₉.  We observe that the magnetic chain axis is along a direction nearly perpendicular to the apparent structural chains which exist in the compound.  Although the system exhibits long range magnetic order below T_N~5 K, we can consistently reproduce the spinon spectrum over a range of higher temperatures and energy transfers via comparisons to Bethe ansatz calculations, matrix renormalization group (DMRG) calculations, and effective field theories near the antiferromagnetic zone center. 

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.  The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.  The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).