Soft antiphase tilt of oxygen octahedra in the hybrid improper multiferroic Ca3Mn1.9Ti0.1O7

Abstract

We report a single crystal neutron and x-ray diffraction study of the hybrid improper multiferroic Ca3Mn1.9Ti0.1O7 (CMTO), a prototypical system where the electric polarization arises from the condensation of two lattice distortion modes.With increasing temperature (T ), the out-of-plane, antiphase tilt of MnO6 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 (P) to CMTO at room temperature shows a similar effect. The consistent behavior under both T and P reveals the softness of antiphase tilt and highlights the role of the partially occupied d 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 0.04 μB/Mn site, despite a substantial out-of-plane tilt of the MnO6 octahedra.

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Cited by in corpus (4)

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• Nature of the Structural Symmetries Associated with Hybrid Improper Ferroelectricity in Ca3X2O7
• Probing $C{a}_{3}T{i}_2{O}_7$ crystal structure at the atomic level: Insights from ${}^{111m}Cd{/}^{111}Cd$ PAC spectroscopy and ab-initio studies