Magnetic excitations in the spin chain candidate Sr2​V3​O9​ have been
investigated by inelastic neutron scattering on a single crystal sample. A
spinon continuum with a bandwidth of ∼22 meV is observed along the chain
formed by alternating magnetic V4+ and nonmagnetic V5+ ions.
Incipient magnetic Bragg peaks due to weak ferromagnetic interchain couplings
emerge when approaching the magnetic transition at TN​∼5.3 K while the
excitations remain gapless within the instrumental resolution. Comparisons to
the Bethe ansatz, density matrix renormalization group (DMRG) calculations, and
effective field theories confirm Sr2​V3​O9​ as a host of weakly coupled
S=1/2 chains dominated by antiferromagnetic intrachain interactions of
∼7.1(1) meV.Comment: 19 pages, 9 figures. arXiv admin note: text overlap with
arXiv:2102.0837