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Journal article
Electric-field-tunable electronic nematic order in twisted double-bilayer graphene
2d materials, v 8(3), 034005
01 Jul 2021
Abstract
Graphene-based moire systems have attracted considerable interest in recent years as they display a remarkable variety of correlated phenomena. Besides insulating and superconducting phases in the vicinity of integer fillings of the moire unit cell, there is growing evidence for electronic nematic order both in twisted bilayer graphene and twisted double-bilayer graphene (tDBG), as signaled by the spontaneous breaking of the threefold rotational symmetry of the moire superlattices. Here, we combine symmetry-based analysis with a microscopic continuum model to investigate the structure of the nematic phase of tDBG and its experimental manifestations. First, we perform a detailed comparison between the theoretically calculated local density of states and recent scanning tunneling microscopy data (arXiv:2009.11645) to resolve the internal structure of the nematic order parameter in terms of the layer, sublattice, spin, and valley degrees of freedom. We find strong evidence that the dominant contribution to the nematic order parameter comes from states at the moire scale rather than at the microscopic scale of the individual graphene layers, which demonstrates the key role played by the moire degrees of freedom and confirms the correlated nature of the nematic phase in tDBG. Secondly, our analysis reveals an unprecedented tunability of the orientation of the nematic director in tDBG by an externally applied electric field, allowing the director to rotate away from high-symmetry crystalline directions. We compute the expected fingerprints of this rotation in both STM and transport experiments, providing feasible ways to probe it. Rooted in the strong sensitivity of the flat bands of tDBG to the displacement field, this effect opens an interesting route to the electrostatic control of electronic nematicity in moire systems.
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Details
- Title
- Electric-field-tunable electronic nematic order in twisted double-bilayer graphene
- Creators
- Rhine Samajdar - Universität InnsbruckMathias S. Scheurer - Universität InnsbruckSimon Turkel - Columbia UniversityCarmen Rubio-Verdu - Columbia UniversityAbhay N. Pasupathy - Columbia UniversityJorn W. F. Venderbos - Drexel UniversityRafael M. Fernandes - University of Minnesota
- Publication Details
- 2d materials, v 8(3), 034005
- Publisher
- IOP Publishing Ltd
- Number of pages
- 20
- Grant note
- FA9550-16-1-0601 / Air Force Office of Scientific Research (AFOSR); United States Department of Defense DE-SC0020045 / U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division; United States Department of Energy (DOE) DMR-2002850 / National Science Foundation; National Science Foundation (NSF) 844271 / European Union Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant; Marie Curie Actions
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics; Materials Science and Engineering; Drexel University
- Web of Science ID
- WOS:000655603300001
- Scopus ID
- 2-s2.0-85106549444
- Other Identifier
- 991021860666004721
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Materials Science, Multidisciplinary
- Nanoscience & Nanotechnology
- Physics, Applied