Magnetic phase diagram and ordered ground state of GdMn2O5 multiferroic studied by x-ray magnetic scattering

Abstract

The magnetic structure of multiferroic GdMn2O5 is studied by x-ray magnetic scattering, both off resonance and in resonant conditions at the Gd LIII edge. Temperature dependence of magnetic Bragg reflections shows an initial incommensurate (ICM) ordering appearing at T~40K with magnetic propagation vector kICM ~(0.49 0 0.18) which condenses at T~33K in a commensurate (CM) wave vector kCM=(½ 0 0). In the CM phase Gd3+ ions appear to order spontaneously at the same temperature as Mn ions. Azimuthal scans allowed for the precise determination, from x-ray magnetic scattering only, of the orientation and magnitude of the Gd3+ magnetic moments. The Gd3+ magnetic isotropy allows for the Gd ions to mimic the Mn4+ magnetic sublattice via Gd-Mn-Gd superexchange interactions.