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Title: Tunneling Hot Spots in Ferroelectric SrTiO 3

Abstract

Strontium titanate (SrTiO3) is the “silicon” in the emerging field of oxide electronics. While bulk properties of this material have been studied for decades, new unexpected phenomena have recently been discovered at the nanoscale, when SrTiO3 forms an ultrathin film or an atomically sharp interface with other materials. One of the striking discoveries is room-temperature ferroelectricity in strain-free ultrathin films of SrTiO3 driven by the TiSr antisite defects, which generate a local dipole moment polarizing the surrounding nanoregion. Here, we demonstrate that these polar defects are not only responsible for ferroelectricity, but also propel the appearance of highly conductive channels, “hot spots”, in the ultrathin SrTiO3 films. Using a combination of scanning probe microscopy experimental studies and theoretical modeling, we show that the hot spots emerge due to resonant tunneling through localized electronic states created by the polar defects and that the tunneling conductance of the hot spots is controlled by ferroelectric polarization. Our finding of the polarization-controlled defect-assisted tunneling reveals a new mechanism of resistive switching in oxide heterostructures and may have technological implications for ferroelectric tunnel junctions. It is also shown that the conductivity of the hot spots can be modulated by mechanical stress, opening a possibility formore » development of conceptually new electronic devices with mechanically tunable resistive states.« less

Authors:
 [1];  [2]; ORCiD logo [3];  [1];  [4];  [2];  [2];  [1];  [4];  [5];  [6];  [2]; ORCiD logo [5]
  1. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States
  2. Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
  3. Department of Chemical and Biomolecular Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
  4. Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
  5. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States; Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, United States
  6. Department of Chemical and Biomolecular Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States; Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588, United States
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1484747
Grant/Contract Number:  
FG02-06ER46327; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 18; Journal Issue: 1; Journal ID: ISSN 1530-6984
Country of Publication:
United States
Language:
English

Citation Formats

Lu, Haidong, Lee, Daesu, Klyukin, Konstantin, Tao, Lingling, Wang, Bo, Lee, Hyungwoo, Lee, Jungwoo, Paudel, Tula R., Chen, Long-Qing, Tsymbal, Evgeny Y., Alexandrov, Vitaly, Eom, Chang-Beom, and Gruverman, Alexei. Tunneling Hot Spots in Ferroelectric SrTiO 3. United States: N. p., 2017. Web. doi:10.1021/acs.nanolett.7b04444.
Lu, Haidong, Lee, Daesu, Klyukin, Konstantin, Tao, Lingling, Wang, Bo, Lee, Hyungwoo, Lee, Jungwoo, Paudel, Tula R., Chen, Long-Qing, Tsymbal, Evgeny Y., Alexandrov, Vitaly, Eom, Chang-Beom, & Gruverman, Alexei. Tunneling Hot Spots in Ferroelectric SrTiO 3. United States. doi:10.1021/acs.nanolett.7b04444.
Lu, Haidong, Lee, Daesu, Klyukin, Konstantin, Tao, Lingling, Wang, Bo, Lee, Hyungwoo, Lee, Jungwoo, Paudel, Tula R., Chen, Long-Qing, Tsymbal, Evgeny Y., Alexandrov, Vitaly, Eom, Chang-Beom, and Gruverman, Alexei. Fri . "Tunneling Hot Spots in Ferroelectric SrTiO 3". United States. doi:10.1021/acs.nanolett.7b04444. https://www.osti.gov/servlets/purl/1484747.
@article{osti_1484747,
title = {Tunneling Hot Spots in Ferroelectric SrTiO 3},
author = {Lu, Haidong and Lee, Daesu and Klyukin, Konstantin and Tao, Lingling and Wang, Bo and Lee, Hyungwoo and Lee, Jungwoo and Paudel, Tula R. and Chen, Long-Qing and Tsymbal, Evgeny Y. and Alexandrov, Vitaly and Eom, Chang-Beom and Gruverman, Alexei},
abstractNote = {Strontium titanate (SrTiO3) is the “silicon” in the emerging field of oxide electronics. While bulk properties of this material have been studied for decades, new unexpected phenomena have recently been discovered at the nanoscale, when SrTiO3 forms an ultrathin film or an atomically sharp interface with other materials. One of the striking discoveries is room-temperature ferroelectricity in strain-free ultrathin films of SrTiO3 driven by the TiSr antisite defects, which generate a local dipole moment polarizing the surrounding nanoregion. Here, we demonstrate that these polar defects are not only responsible for ferroelectricity, but also propel the appearance of highly conductive channels, “hot spots”, in the ultrathin SrTiO3 films. Using a combination of scanning probe microscopy experimental studies and theoretical modeling, we show that the hot spots emerge due to resonant tunneling through localized electronic states created by the polar defects and that the tunneling conductance of the hot spots is controlled by ferroelectric polarization. Our finding of the polarization-controlled defect-assisted tunneling reveals a new mechanism of resistive switching in oxide heterostructures and may have technological implications for ferroelectric tunnel junctions. It is also shown that the conductivity of the hot spots can be modulated by mechanical stress, opening a possibility for development of conceptually new electronic devices with mechanically tunable resistive states.},
doi = {10.1021/acs.nanolett.7b04444},
journal = {Nano Letters},
number = 1,
volume = 18,
place = {United States},
year = {2017},
month = {12}
}

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