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Title: Dynamic interface rearrangement in LaFeO 3 / n SrTiO 3 heterojunctions

Abstract

Thin film synthesis methods developed over the past decades have unlocked emergent interface properties ranging from conductivity to ferroelectricity. However, our attempts to exercise precise control over interfaces are constrained by a limited understanding of growth pathways and kinetics. Here we demonstrate that shuttered molecular beam epitaxy induces rearrangements of atomic planes at a polar / non- polar junction of LaFeO3 (LFO) / n-SrTiO3 (STO) depending on the substrate termination. Surface characterization confirms that substrates with two different (TiO2 and SrO) terminations were prepared prior to LFO deposition; however, local electron energy loss spectroscopy measurements of the final heterojunctions show a predominantly LaO / TiO2 interfacial junction in both cases. Ab initio simulations suggest that the interfaces can be stabilized by trapping extra oxygen (in LaO / TiO2) and forming oxygen vacancies (in FeO2 / SrO), which points to different growth kinetics at these interfaces and may explain the apparent disappearance of the FeO2 / SrO interface. We conclude that judicious control of deposition timescales can be used to modify growth pathways, opening new avenues to control the structure and properties of interfacial systems.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1424836
Report Number(s):
PNNL-SA-127972
Journal ID: ISSN 2475-9953; PRMHAR; 49306; KC0203020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Materials; Journal Volume: 1; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
scanning transmission electron microscopy (STEM); electron energy loss spectroscopy; Density Functional Theory; oxide thin films; Environmental Molecular Sciences Laboratory

Citation Formats

Spurgeon, Steven R., Sushko, Peter V., Chambers, Scott A., and Comes, Ryan B. Dynamic interface rearrangement in LaFeO3/n−SrTiO3 heterojunctions. United States: N. p., 2017. Web. doi:10.1103/PhysRevMaterials.1.063401.
Spurgeon, Steven R., Sushko, Peter V., Chambers, Scott A., & Comes, Ryan B. Dynamic interface rearrangement in LaFeO3/n−SrTiO3 heterojunctions. United States. doi:10.1103/PhysRevMaterials.1.063401.
Spurgeon, Steven R., Sushko, Peter V., Chambers, Scott A., and Comes, Ryan B. Wed . "Dynamic interface rearrangement in LaFeO3/n−SrTiO3 heterojunctions". United States. doi:10.1103/PhysRevMaterials.1.063401.
@article{osti_1424836,
title = {Dynamic interface rearrangement in LaFeO3/n−SrTiO3 heterojunctions},
author = {Spurgeon, Steven R. and Sushko, Peter V. and Chambers, Scott A. and Comes, Ryan B.},
abstractNote = {Thin film synthesis methods developed over the past decades have unlocked emergent interface properties ranging from conductivity to ferroelectricity. However, our attempts to exercise precise control over interfaces are constrained by a limited understanding of growth pathways and kinetics. Here we demonstrate that shuttered molecular beam epitaxy induces rearrangements of atomic planes at a polar / non- polar junction of LaFeO3 (LFO) / n-SrTiO3 (STO) depending on the substrate termination. Surface characterization confirms that substrates with two different (TiO2 and SrO) terminations were prepared prior to LFO deposition; however, local electron energy loss spectroscopy measurements of the final heterojunctions show a predominantly LaO / TiO2 interfacial junction in both cases. Ab initio simulations suggest that the interfaces can be stabilized by trapping extra oxygen (in LaO / TiO2) and forming oxygen vacancies (in FeO2 / SrO), which points to different growth kinetics at these interfaces and may explain the apparent disappearance of the FeO2 / SrO interface. We conclude that judicious control of deposition timescales can be used to modify growth pathways, opening new avenues to control the structure and properties of interfacial systems.},
doi = {10.1103/PhysRevMaterials.1.063401},
journal = {Physical Review Materials},
number = 6,
volume = 1,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}