title: Ultrafast atomic layer-by-layer oxygen vacancy-exchange diffusion in double-perovskite LnBaCo2O5.5+δ thin films.
abstract: Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 < δ < 0.5) by carefully monitoring the resistance changes under a switching flow of oxidizing gas (O2) and reducing gas (H2) in the temperature range of 250 ~ 800 °C. A giant resistance change ΔR by three to four orders of magnitude in less than 0.1 s was found with a fast oscillation behavior in the resistance change rates in the ΔR vs. t plots, suggesting that the oxygen vacancy exchange diffusion with oxygen/hydrogen atoms in the LnBCO thin films is taking the layer by layer oxygen-vacancy-exchange mechanism. The first principles density functional theory calculations indicate that hydrogen atoms are present in LnBCO as bound to oxygen forming O-H bonds. This unprecedented oscillation phenomenon provides the first direct experimental evidence of the layer by layer oxygen vacancy exchange diffusion mechanism.
authors.affiliation: 1] Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA [2] Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China.
authors.forename: Shanyong
authors.initials: S
authors.lastname: Bao
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA.
authors.forename: Chunrui
authors.initials: C
authors.lastname: Ma
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA.
authors.forename: Garry
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA.
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Enriquez
authors.affiliation: 1] Department of Physics and Astronomy, University of Texas at San Antonio, TX 78249, USA [2] The Texas Center for Superconductivity, University of Houston, TX 77204, USA.
authors.forename: Chonglin
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Physics, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, China.
authors.forename: Yamei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Bettis
authors.affiliation: North Carolina State University, Raleigh, NC 27695-8204, USA.
authors.forename: Myung-Hwan
authors.initials: MH
authors.lastname: Whangbo
authors.affiliation: Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China.
authors.forename: Chuang
authors.initials: C
authors.lastname: Dong
authors.affiliation: Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, China.
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Zhang
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