Abstract
We report a single crystal neutron and x-ray diffraction study of the hybrid improper multiferroic (CMTO), a prototypical system where the electric polarization arises from the condensation of two lattice distortion modes. With increasing temperature (), the out-of-plane, antiphase tilt of decreases in amplitude while the in-plane, in-phase rotation remains robust and experiences abrupt changes across the first-order structural transition. Application of hydrostatic pressure () to CMTO at room temperature shows a similar effect. The consistent behavior under both and reveals the softness of antiphase tilt and highlights the role of the partially occupied orbital of the transition-metal ions in determining the stability of the octahedral distortion. Polarized neutron analysis indicates the symmetry-allowed canted ferromagnetic moment is less than the site, despite a substantial out-of-plane tilt of the octahedra.
- Received 24 July 2017
DOI:https://doi.org/10.1103/PhysRevB.97.041112
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