Charge and orbital order in the electron doped magnanite (Bi,Ca)MnO 3

Abstract

The interplay between charge, spin and orbital degrees of freedom in transition metal oxides has been a matter of much interest in recent years. In this paper we present X-ray scattering results of charge and orbital ordering in the electron doped manganite Bi 0.24Ca 0.76MnO 3. Using High Energy X-ray Scattering (HEXS) the charge ordering, structural modulation due to the Jahn–Teller ordering and the harmonic of the structural modulation have been measured. The superlattice reflections due to the Jahn–Teller ordering are found to maximise in intensity at the Neél point. We have confirmed using resonant X-ray scattering at the K-edge of manganese and the anisotropic tensor of susceptibility technique (ATS) that superlattice reflections occurring at a modulation wave vector of (0.5, 0, 0) are due to charge ordering in a Mn 3+/Mn 4+ ordering pattern. In addition superlattice reflections corresponding to the orbital order were measured at a modulation wave vector of (0.25, 0, 0). From the temperature dependence of the orbital and charge order it appears that the orbital order is driven by the charge order.