Evolution of the commensurate and incommensurate magnetic phases of the S?=?3/2 kagome staircase Co3V2O8?in an applied field

Single crystal neutron diffraction studies have been performed on the S = 3/2 kagome staircase compound Co3V2O8 with a magnetic field applied along the magnetization easy-axis (). Previous zero-field measurements (Chen Y et al 2006 Phys. Rev. B 74 014430) reported a rich variety of magnetic phases, with a ferromagnetic ground state as well as incommensurate, transversely polarized spin density wave (SDW) phases (with a propagation vector of ) interspersed with multiple commensurate lock-in transitions. The magnetic phase diagram with adds further complexity. For small applied fields, μ0H ≈ 0.05 T, the commensurate lock-in phases are destabilized in favor of the incommensurate SDW ones, while slightly larger applied fields restore the commensurate lock-in phase with δ = 1/2 and yield a new commensurate phase with δ = 2/5. For measurements in an applied field, higher-order scattering is observed that corresponds to the second harmonic.