Unconventional ferroelectricity in moiré heterostructures
Name
BLG_moireFE_maintext_figures.pdf
Size
3.54 MB
Format
Adobe PDF
Checksum (MD5)
b8981230797f948fa361de0c9dbe575a
Author(s)
Zheng, Zhiren
Ma, Qiong
Bi, Zhen
de la Barrera, Sergio
Liu, Ming-Hao
Mao, Nannan
Zhang, Yang
Kiper, Natasha
Watanabe, Kenji
Taniguchi, Takashi
Date Issued
November 2020
Journal
Nature
Publisher
Springer Science and Business Media LLC
Citation
Zheng, Zhiren et al. "Unconventional ferroelectricity in moiré heterostructures." Nature 588, 7836 (November 2020): 71–76 © 2020 The Author(s)
Version
Author's final manuscript
Abstract
The constituent particles of matter can arrange themselves in various ways, giving rise to emergent phenomena that can be surprisingly rich and often cannot be understood by studying only the individual constituents. Discovering and understanding the emergence of such phenomena in quantum materials—especially those in which multiple degrees of freedom or energy scales are delicately balanced—is of fundamental interest to condensed-matter research. Here we report on the surprising observation of emergent ferroelectricity in graphene-based moiré heterostructures. Ferroelectric materials show electrically switchable electric dipoles, which are usually formed by spatial separation between the average centres of positive and negative charge within the unit cell. On this basis, it is difficult to imagine graphene—a material composed of only carbon atoms—exhibiting ferroelectricity3. However, in this work we realize switchable ferroelectricity in Bernal-stacked bilayer graphene sandwiched between two hexagonal boron nitride layers. By introducing a moiré superlattice potential (via aligning bilayer graphene with the top and/or bottom boron nitride crystals), we observe prominent and robust hysteretic behaviour of the graphene resistance with an externally applied out-of-plane displacement field. Our systematic transport measurements reveal a rich and striking response as a function of displacement field and electron filling, and beyond the framework of conventional ferroelectrics. We further directly probe the ferroelectric polarization through a non-local monolayer graphene sensor. Our results suggest an unconventional, odd-parity electronic ordering in the bilayer graphene/boron nitride moiré system. This emergent moiré ferroelectricity may enable ultrafast, programmable and atomically thin carbon-based memory devices.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Materials Research Laboratory
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1038/s41586-020-2970-9
