Polar phase transitions in heteroepitaxial stabilized La0.5Y0.5AlO3 thin films

Shenghua Liu; Chunfeng Zhang; Mengya Zhu; Qian He; Jak Chakhalian; Xiaoran Liu; Albina Borisevich; Xiaoyong Wang; Min Xiao

doi:10.1088/1361-648X/aa81ea

Polar phase transitions in heteroepitaxial stabilized La_0.5Y_0.5AlO₃ thin films

Shenghua Liu, Chunfeng Zhang, Mengya Zhu, Qian He, Jak Chakhalian, Xiaoran Liu, Albina Borisevich, Xiaoyong Wang, Min Xiao

electron Microscopy and Microanalysis

Research output: Contribution to journal › Article › peer-review

Abstract

We report on the fabrication of epitaxial La_0.5Y_0.5AlO₃ ultrathin films on (001) LaAlO₃ substrates. Structural characterizations by scanning transmission electron microscopy and x-ray diffraction confirm the high quality of the film with a ^- b ⁺ c ^- AlO₆ octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO₃ and YAlO₃, second harmonic generation measurements on the thin films suggest a nonpolar-polar phase transition at T _c near 500 K, and a polar-polar phase transition at T _a near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc2 ₁ and Pmn2 ₁ space group, while the high temperature nonpolar structure belongs to the Pbnm space group.

Original language	English
Article number	405401
Journal	Journal of Physics Condensed Matter
Volume	29
Issue number	40
DOIs	https://doi.org/10.1088/1361-648X/aa81ea
State	Published - Sep 1 2017

Funding

The authors thank J Young, J Rondinelli, and L Bellaiche for fruitful discussions. Also we acknowledge beamline BL14B1 (Shanghai Synchrotron Radiation Facility) for providing the beam time and assistance during experiments. CZ acknowledges Xuewei Wu for his technical assistant. Research at Nanjing University is supported by the National Basic Research Program of China (2013CB932903), the National Science Foundation of China (11574140, and 11621091), and Jiangsu Provincial Funds for Distinguished Young Scientists (BK20160019). Electron microscopy study (QH, AYB) was supported by the US DOE, Office of Sciene, Basic Energy Sciences, Materials Sciences and Engineering Division. JC acknowledges the support by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant No. GMBF4534. XL acknowledges the support by the Department of Energy Grant No. DE-SC0012375.

Funders	Funder number
Office of Sciene
U.S. Department of Energy
Gordon and Betty Moore Foundation
Basic Energy Sciences
Division of Materials Sciences and Engineering
National Natural Science Foundation of China	11574140, 11621091
China National Funds for Distinguished Young Scientists	BK20160019
National Basic Research Program of China (973 Program)	2013CB932903

Keywords

eptaxial growth
polar structure
provskite oxide

Access to Document

10.1088/1361-648X/aa81ea

Cite this

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title = "Polar phase transitions in heteroepitaxial stabilized La0.5Y0.5AlO3 thin films",

abstract = "We report on the fabrication of epitaxial La0.5Y0.5AlO3 ultrathin films on (001) LaAlO3 substrates. Structural characterizations by scanning transmission electron microscopy and x-ray diffraction confirm the high quality of the film with a - b + c - AlO6 octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO3 and YAlO3, second harmonic generation measurements on the thin films suggest a nonpolar-polar phase transition at T c near 500 K, and a polar-polar phase transition at T a near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc2 1 and Pmn2 1 space group, while the high temperature nonpolar structure belongs to the Pbnm space group.",

keywords = "eptaxial growth, polar structure, provskite oxide",

author = "Shenghua Liu and Chunfeng Zhang and Mengya Zhu and Qian He and Jak Chakhalian and Xiaoran Liu and Albina Borisevich and Xiaoyong Wang and Min Xiao",

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T1 - Polar phase transitions in heteroepitaxial stabilized La0.5Y0.5AlO3 thin films

AU - Liu, Shenghua

AU - Zhang, Chunfeng

AU - Zhu, Mengya

AU - He, Qian

AU - Chakhalian, Jak

AU - Liu, Xiaoran

AU - Borisevich, Albina

AU - Wang, Xiaoyong

AU - Xiao, Min

PY - 2017/9/1

Y1 - 2017/9/1

N2 - We report on the fabrication of epitaxial La0.5Y0.5AlO3 ultrathin films on (001) LaAlO3 substrates. Structural characterizations by scanning transmission electron microscopy and x-ray diffraction confirm the high quality of the film with a - b + c - AlO6 octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO3 and YAlO3, second harmonic generation measurements on the thin films suggest a nonpolar-polar phase transition at T c near 500 K, and a polar-polar phase transition at T a near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc2 1 and Pmn2 1 space group, while the high temperature nonpolar structure belongs to the Pbnm space group.

AB - We report on the fabrication of epitaxial La0.5Y0.5AlO3 ultrathin films on (001) LaAlO3 substrates. Structural characterizations by scanning transmission electron microscopy and x-ray diffraction confirm the high quality of the film with a - b + c - AlO6 octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO3 and YAlO3, second harmonic generation measurements on the thin films suggest a nonpolar-polar phase transition at T c near 500 K, and a polar-polar phase transition at T a near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc2 1 and Pmn2 1 space group, while the high temperature nonpolar structure belongs to the Pbnm space group.

KW - eptaxial growth

KW - polar structure

KW - provskite oxide

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