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Title: Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1354472
Report Number(s):
BNL-112989-2016-JA
Journal ID: ISSN 2045-2322
DOE Contract Number:
SC00112704
Resource Type:
Journal Article
Resource Relation:
Journal Name: Scientific Reports; Journal Volume: 6; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Dubuis, Guy, Yacoby, Yizhak, Zhou, Hua, He, Xi, Bollinger, Anthony T., Pavuna, Davor, Pindak, Ron, and Božović, Ivan. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating. United States: N. p., 2016. Web. doi:10.1038/srep32378.
Dubuis, Guy, Yacoby, Yizhak, Zhou, Hua, He, Xi, Bollinger, Anthony T., Pavuna, Davor, Pindak, Ron, & Božović, Ivan. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating. United States. doi:10.1038/srep32378.
Dubuis, Guy, Yacoby, Yizhak, Zhou, Hua, He, Xi, Bollinger, Anthony T., Pavuna, Davor, Pindak, Ron, and Božović, Ivan. 2016. "Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating". United States. doi:10.1038/srep32378.
@article{osti_1354472,
title = {Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating},
author = {Dubuis, Guy and Yacoby, Yizhak and Zhou, Hua and He, Xi and Bollinger, Anthony T. and Pavuna, Davor and Pindak, Ron and Božović, Ivan},
abstractNote = {},
doi = {10.1038/srep32378},
journal = {Scientific Reports},
number = 1,
volume = 6,
place = {United States},
year = 2016,
month = 8
}
  • We studied structural changes in a 5 unit cell thick La 1.96Sr 0.04CuO 4 film, epitaxially grown on a LaSrAlO 4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. When measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. Furthermore, the mainmore » structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.« less
  • Here, we studied structural changes in a 5 unit cell thick La 1.96Sr 0.04CuO 4 film, epitaxially grown on a LaSrAlO 4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structuralmore » observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.« less
  • We studied structural changes in a 5 unit cell thick La 1.96Sr 0.04CuO 4 film, epitaxially grown on a LaSrAlO 4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were:more » (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and planar oxygen atoms were displaced towards the sample surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of planar oxygen atoms.« less
  • The effect of gate voltage polarity on the behavior of NdNiO 3 epitaxial thin films during ionic liquid gating is studied using in situ synchrotron X-ray techniques. We show that while negative biases have no discernible effect on the structure or composition of the films, large positive gate voltages result in the injection of a large concentration of oxygen vacancies (similar to 3%) and pronounced lattice expansion (0.17%) in addition to a 1000-fold increase in sheet resistance at room temperature. Despite the creation of large defect densities, the heterostructures exhibit a largely reversible switching behavior when sufficient time is providedmore » for the vacancies to migrate in and out of the thin film surface. The results confirm that electrostatic gating takes place at negative gate voltages for p-type complex oxides while positive voltages favor the electrochemical reduction of Ni 3+. Switching between positive and negative gate voltages therefore involves a combination of electronic and ionic doping processes that may be utilized in future electrochemical transistors.« less