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arXiv · 1801.06465

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

Feng Ye·Jinchen Wang·Jieming Sheng·C. Hoffmann·T. Gu·H. J. Xiang·Wei Tian·J. J. Molaison·A. M. dos Santos·M. Matsuda·B. C. Chakoumakos·J. A. Fernandez-Baca·X. Tong·Bin Gao·Jae Wook Kim·S. -W. Cheong
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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 {\mu}B/Mn site, despite a substantial out-of-plane tilt of the MnO6 octahedra.

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Feng Ye, Jinchen Wang, Jieming Sheng, C. Hoffmann, T. Gu, H. J. Xiang, Wei Tian, J. J. Molaison, A. M. dos Santos, M. Matsuda, B. C. Chakoumakos, J. A. Fernandez-Baca, X. Tong, Bin Gao, Jae Wook Kim, S. -W. Cheong. 2018-01-19. Soft antiphase tilt of oxygen octahedra in the hybrid improper multiferroic Ca3Mn1.9Ti0.1O7. https://doi.org/10.1103/physrevb.97.041112

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