Resonant x-ray scattering study on multiferroic BiMnO3

TL;DR

This study uses resonant x-ray scattering to investigate the orbital ordering in BiMnO3 thin films, revealing temperature-dependent features linked to structural transitions and potential connections to ferroelectricity.

Contribution

It provides the first detailed analysis of Mn orbital ordering in BiMnO3 using resonant x-ray scattering, highlighting temperature effects and structural correlations.

Findings

Resonant peak persists up to 770 K.

Anomaly observed around 440 K correlating with structural transition.

Azimuthal angle dependence reveals orbital ordering patterns.

Abstract

Resonant x-ray scattering is performed near the Mn K-absorption edge for an epitaxial thin film of BiMnO3. The azimuthal angle dependence of the resonant (003) peak (in monoclinic indices) is measured with different photon polarizations; for the $\sigma\to\pi'$ channel a 3-fold symmetric oscillation is observed in the intensity variation, while the $\sigma\to\sigma'$ scattering intensity remains constant. These features are accounted for in terms of the peculiar ordering of the manganese 3d orbitals in BiMnO3. It is demonstrated that the resonant peak persists up to 770 K with an anomaly around 440 K; these high and low temperatures coincide with the structural transition temperatures, seen in bulk, with and without a symmetry change, respectively. A possible relationship of the orbital order with the ferroelectricity of the system is discussed.