Spinons in the strongly correlated copper oxide chains in SrCuO2

Abstract

We have investigated the spin dynamics in the strongly correlated chain copper oxide SrCuO2 for energies up to ≥0.6 eV using inelastic neutron scattering. We observe a gapless continuum of magnetic excitations, which is well described by the 'Muller ansatz' for the two-spinon continuum in the S=1/2 antiferromagnetic Heisenberg spin chain. The lower boundary of the continuum extends up to ≈360 meV, which corresponds to an exchange constant J=226(12) meV.