American Institute of Physics, Applied Physics Letters, 16(106), p. 162904
DOI: 10.1063/1.4918805
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Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO3, through the careful control of the biaxial strain state and TiO6 octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO3 films grown on La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) and NdGaO3 (NGO) substrates experienced a 1.1% biaxial strain state but differed in their octahedral tilt structures. A suppression of the out-of-plane rotations of the TiO6 octahedral in films grown on LSAT substrates resulted in a robust ferroelectric I4 mm phase with remnant polarization similar to 5 mu C/cm(2) at 10 K and T-c near 140 K. In contrast, films grown on NGO substrates with significant octahedral tilting showed reduced polarization and T-c. These results highlight the key role played by symmetry in controlling the ferroelectric properties of perovskite oxide thin films. (C) 2015 AIP Publishing LLC. ; ISI Document Delivery No.: CG8LS Times Cited: 0 Cited Reference Count: 20 Biegalski, Michael D. Qiao, Liang Gu, Yijia Mehta, Apurva He, Qian Takamura, Yayoi Borisevich, Albina Chen, Long-Qing U.S. DOE, Office of Science, Office of Basic Energy Sciences [DE-AC02-76SF00515]; U.S. DOE, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division The sample growth and characterization in this research were conducted at the Center for Nanophase Materials Sciences, which is a Department of Energy (DOE) Office of Science User Facility. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, was supported by the U.S. DOE, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Y.T. acknowledges the National Science Foundation (NSF, DMR 0747896); Y.G. and L.Q.C. acknowledge NSF (DMR 1410701, DMR 1420620). Electron microscopy research (Q.H. and A.B.) was supported by the U.S. DOE, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The authors L.Q.,Y.G., A.M., Q.H., A.B., L.Q.C., and Y.T. submit this paper in honor and in memory of Michael Biegalski who was not only a well-respected research colleague but also a wonderful father and husband, a driven athlete, and a dear friend to all of us. Amer inst physics Melville