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Title: Ferroelectric switching of a two-dimensional metal

Abstract

A ferroelectric is a material with a polar structure whose polarity can be reversed (switched) by applying an electric field. In metals, itinerant electrons screen electrostatic forces between ions, which explains in part why polar metals are very rare. Screening also excludes external electric fields, apparently ruling out the possibility of ferroelectric switching. However, in principle, a thin enough polar metal could be sufficiently penetrated by an electric field to have its polarity switched. In this paper we show that the topological semimetal WTe 2 provides an embodiment of this principle. Although monolayer WTe 2 is centro-symmetric and thus non-polar, the stacked bulk structure is polar. We find that two- or three-layer WTe 2 exhibits spontaneous out-of-plane electric polarization that can be switched using gate electrodes. We directly detect and quantify the polarization using graphene as an electric-field sensor. Moreover, the polarization states can be differentiated by conductivity and the carrier density can be varied to modify the properties. Finally, the temperature at which polarization vanishes is above 350 kelvin, and even when WTe 2 is sandwiched between graphene layers it retains its switching capability at room temperature, demonstrating a robustness suitable for applications in combination with other two-dimensional materials.

Authors:
 [1];  [1];  [1];  [1];  [1];  [2];  [3];  [4];  [1]
  1. Univ. of Washington, Seattle, WA (United States). Dept. of Physics
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  4. Univ. of Washington, Seattle, WA (United States). Dept. of Physics. Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
OSTI Identifier:
1462831
Grant/Contract Number:  
AC05-00OR22725; SC0002197; SC0018171; DMR-1420451; FA9550-14-1-0277; EFRI 2DARE 1433496; MRSEC 1719797
Resource Type:
Accepted Manuscript
Journal Name:
Nature (London)
Additional Journal Information:
Journal Name: Nature (London); Journal Volume: 560; Journal ID: ISSN 0028-0836
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ferroelectrics and multiferroics; two-dimensional materials

Citation Formats

Fei, Zaiyao, Zhao, Wenjin, Palomaki, Tauno A., Sun, Bosong, Miller, Moira K., Zhao, Zhiying, Yan, Jiaqiang, Xu, Xiaodong, and Cobden, David H. Ferroelectric switching of a two-dimensional metal. United States: N. p., 2018. Web. doi:10.1038/s41586-018-0336-3.
Fei, Zaiyao, Zhao, Wenjin, Palomaki, Tauno A., Sun, Bosong, Miller, Moira K., Zhao, Zhiying, Yan, Jiaqiang, Xu, Xiaodong, & Cobden, David H. Ferroelectric switching of a two-dimensional metal. United States. doi:10.1038/s41586-018-0336-3.
Fei, Zaiyao, Zhao, Wenjin, Palomaki, Tauno A., Sun, Bosong, Miller, Moira K., Zhao, Zhiying, Yan, Jiaqiang, Xu, Xiaodong, and Cobden, David H. Mon . "Ferroelectric switching of a two-dimensional metal". United States. doi:10.1038/s41586-018-0336-3. https://www.osti.gov/servlets/purl/1462831.
@article{osti_1462831,
title = {Ferroelectric switching of a two-dimensional metal},
author = {Fei, Zaiyao and Zhao, Wenjin and Palomaki, Tauno A. and Sun, Bosong and Miller, Moira K. and Zhao, Zhiying and Yan, Jiaqiang and Xu, Xiaodong and Cobden, David H.},
abstractNote = {A ferroelectric is a material with a polar structure whose polarity can be reversed (switched) by applying an electric field. In metals, itinerant electrons screen electrostatic forces between ions, which explains in part why polar metals are very rare. Screening also excludes external electric fields, apparently ruling out the possibility of ferroelectric switching. However, in principle, a thin enough polar metal could be sufficiently penetrated by an electric field to have its polarity switched. In this paper we show that the topological semimetal WTe2 provides an embodiment of this principle. Although monolayer WTe2 is centro-symmetric and thus non-polar, the stacked bulk structure is polar. We find that two- or three-layer WTe2 exhibits spontaneous out-of-plane electric polarization that can be switched using gate electrodes. We directly detect and quantify the polarization using graphene as an electric-field sensor. Moreover, the polarization states can be differentiated by conductivity and the carrier density can be varied to modify the properties. Finally, the temperature at which polarization vanishes is above 350 kelvin, and even when WTe2 is sandwiched between graphene layers it retains its switching capability at room temperature, demonstrating a robustness suitable for applications in combination with other two-dimensional materials.},
doi = {10.1038/s41586-018-0336-3},
journal = {Nature (London)},
number = ,
volume = 560,
place = {United States},
year = {2018},
month = {7}
}

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    Works referencing / citing this record:

    Functional Oxides for Photoneuromorphic Engineering: Toward a Solar Brain
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