A double-spiral spin ordering in the helimagnet YBaCuFeO 5

Abstract Materials with spiral spin ordering always exhibit a rich phase diagram and can be a playground for studying the exotic physical properties associated with spiral magnetism. Using neutron elastic and resonant x-ray scattering on high-quality single crystal YBaCuFeO 5 , we demonstrate YBaCuFeO 5 as a helimagnet consisting of double-spiral spin ordering. YBaCuFeO 5 undergoes a commensurate-to-incommensurate (ICM) magnetic phase transition at T N2 ∼ 175 K, and the ICM phase consists of two spin-ordered components. Both components have different periodicities, but with the same propagating direction along the c -axis below T N2 . Using resonant x-ray scattering at the Fe and Cu K -edges, we further demonstrate that both spiral spin orderings result from the Fe 3 + and Cu 2 + , respectively, forming a double-spiral spin ordering structure. This can be attributed to the coupling between the sublattices of Fe 3 + and Cu 2 + with the atomic lattice.