@article{0f69f7fb460a4d87a2269241e2ac7b59,
title = "Nature of the structural symmetries associated with hybrid improper ferroelectricity in C a3X2 O7 (X=Mn and Ti)",
abstract = "In hybrid improper ferroelectric systems, polarization arises from the onset of successive nonpolar lattice modes. In this work, measurements and modeling were performed to determine the spatial symmetries of the phases involved in the transitions to these modes. Structural and optical measurements reveal that the tilt and rotation distortions of the MnO6 or TiO6 polyhedra relative to the high symmetry phases driving ferroelectricity in the hybrid improper Ca3X2O7 system (X=Mn and Ti) condense at different temperatures. The tilt angle vanishes abruptly at TT∼400 K for Ca3Mn2O7 (and continuously for X=Ti) and the rotation mode amplitude is suppressed at much higher temperatures TR∼1060 K. Moreover, Raman measurements in Ca3Mn2O7 under isotropic pressure reveal that the polyhedral tilts can be suppressed by very low pressures (between 1.4 and 2.3 GPa) indicating their softness. These results indicate that the Ca3Mn2O7 system provides a platform for strain engineering of ferroelectric properties in film-based systems with substrate-induced strain.",
author = "S. Liu and H. Zhang and S. Ghose and M. Balasubramanian and Zhenxian Liu and Wang, {S. G.} and Chen, {Y. S.} and B. Gao and Jaewook Kim and Cheong, {S. W.} and Tyson, {T. A.}",
note = "Funding Information: This work is supported by the National Science Foundation (NSF) Grant No. DMR-1809931. Work at Rutgers University is supported by the U. S. Department of Energy (DOE) Grant No. DE-GF02-07ER46382. This research used beamlines 8-ID, 22-IR-1, and 28-ID-2 of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Single crystal x-ray diffraction measurements were performed at NSF's ChemMatCARS Sector 15, which is principally supported by the NSF/DOE No. NSF/CHE-1834750. Beamline 22-IR-1 is supported by COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 1606856 and the DOE/NNSA (DE-NA-0003858, CDAC). Use of the Advanced Photon Source was supported by the U.S. DOE, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Physical Properties Measurements System was acquired under NSF MRI Grant No. DMR-0923032 (ARRA award). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No. DE-AC02-05CH11231. Funding Information: This work is supported by the National Science Foundation (NSF) Grant No. DMR-1809931. Work at Rutgers University is supported by the U. S. Department of Energy (DOE) Grant No. DE-GF02-07ER46382. This research used beamlines 8-ID, 22-IR-1, and 28-ID-2 of the National Synchrotron Light Source II, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Single crystal x-ray diffraction measurements were performed at NSF's ChemMatCARS Sector 15, which is principally supported by the NSF/DOE No. NSF/CHE-1834750. Beamline 22-IR-1 is supported by COMPRES, the Consortium for Materials Properties Research in Earth Sciences under NSF Cooperative Agreement EAR 1606856 and the DOE/NNSA (DE-NA-0003858, CDAC). Use of the Advanced Photon Source was supported by the U.S. DOE, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Physical Properties Measurements System was acquired under NSF MRI Grant No. DMR-0923032 (ARRA award). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No. DE-AC02-05CH11231. We are indebted to Prof. E. A. Nowadnick of NJIT for critical discussions and advice on simulations and central experiments. Publisher Copyright: {\textcopyright} 2019 American Physical Society. US.",
year = "2019",
month = jun,
day = "27",
doi = "10.1103/PhysRevB.99.224105",
language = "English (US)",
volume = "99",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Institute of Physics",
number = "22",
}