Partial antiferromagnetic helical order in single-crystal Fe3PO4O3

Recently published in Physical Review B:

Magnetic frustration in Fe₃PO₄O₃ produces an unusual magnetic state below Tn = 163K, where incommensurate antiferromagnetic order is restricted to nanosized needle-like domains. We report our single crystal neutron diffraction work, which show continuous rings of scattering in the ab-plane with a well-defined radius. Our analysis show Fe₃PO₄O₃ does not choose a preferred ordering wavevector direction, despite having a fixed magnitude. We reproduce a quasi-degenerate manifold of ordering wavevectors using an antiferromagnetic Heisenberg model with nearest and second neighbor interactions. The state shows a stark similarity to the partially ordered phase of the skyrmion hosting MnSi, but in Fe₃PO₄O₃, the dominant interactions are that of a frustrated antiferromagnet.