title: Phase transitions via selective elemental vacancy engineering in complex oxide thin films.
abstract: Defect engineering has brought about a unique level of control for Si-based semiconductors, leading to the optimization of various opto-electronic properties and devices. With regard to perovskite transition metal oxides, O vacancies have been a key ingredient in defect engineering, as they play a central role in determining the crystal field and consequent electronic structure, leading to important electronic and magnetic phase transitions. Therefore, experimental approaches toward understanding the role of defects in complex oxides have been largely limited to controlling O vacancies. In this study, we report on the selective formation of different types of elemental vacancies and their individual roles in determining the atomic and electronic structures of perovskite SrTiO3 (STO) homoepitaxial thin films fabricated by pulsed laser epitaxy. Structural and electronic transitions have been achieved via selective control of the Sr and O vacancy concentrations, respectively, indicating a decoupling between the two phase transitions. In particular, O vacancies were responsible for metal-insulator transitions, but did not influence the Sr vacancy induced cubic-to-tetragonal structural transition in epitaxial STO thin film. The independent control of multiple phase transitions in complex oxides by exploiting selective vacancy engineering opens up an unprecedented opportunity toward understanding and customizing complex oxide thin films.
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.|Insitute of Basic Science, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Sang A
authors.initials: SA
authors.lastname: Lee
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Hoidong
authors.initials: H
authors.lastname: Jeong
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Sungmin
authors.initials: S
authors.lastname: Woo
authors.affiliation: Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) Sungkyunkwan University, Suwon 16419, Korea.
authors.forename: Jae-Yeol
authors.initials: JY
authors.lastname: Hwang
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science, Changwon 51508, Korea.
authors.forename: Si-Young
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science, Changwon 51508, Korea.
authors.forename: Sung-Dae
authors.initials: SD
authors.lastname: Kim
authors.affiliation: Materials Modeling and Characterization Department, Korea Institute of Materials Science, Changwon 51508, Korea.|Department of Physics, Inha University, Incheon 22212, Korea.
authors.forename: Minseok
authors.initials: M
authors.lastname: Choi
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Seulki
authors.initials: S
authors.lastname: Roh
authors.affiliation: Department of Energy Sciences, Sungkyunkwan University, Suwon 16419, Korea.
authors.forename: Hosung
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Jungseek
authors.initials: J
authors.lastname: Hwang
authors.affiliation: Department of Energy Sciences, Sungkyunkwan University, Suwon 16419, Korea.
authors.forename: Sung Wng
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea.
authors.forename: Woo Seok
authors.initials: WS
authors.lastname: Choi