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Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene

Hsu, C.-C. and Teague, M. L. and Wang, J.-Q. and Yeh, N.-C. (2020) Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene. Science Advances, 6 (19). Art. No. eaat9488. ISSN 2375-2548. PMCID PMC7209983. doi:10.1126/sciadv.aat9488.

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The existence of nontrivial Berry phases associated with two inequivalent valleys in graphene provides interesting opportunities for investigating the valley-projected topological states. Examples of such studies include observation of anomalous quantum Hall effect in monolayer graphene, demonstration of topological zero modes in “molecular graphene” assembled by scanning tunneling microscopy, and detection of topological valley transport either in graphene superlattices or at bilayer graphene domain walls. However, all aforementioned experiments involved nonscalable approaches of either mechanically exfoliated flakes or atom-by-atom constructions. Here, we report an approach to manipulating the topological states in monolayer graphene via nanoscale strain engineering at room temperature. By placing strain-free monolayer graphene on architected nanostructures to induce global inversion symmetry breaking, we demonstrate the development of giant pseudo-magnetic fields (up to ~800 T), valley polarization, and periodic one-dimensional topological channels for protected propagation of chiral modes in strained graphene, thus paving a pathway toward scalable graphene-based valleytronics.

Item Type:Article
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URLURL TypeDescription Information CentralArticle Paper
Hsu, C.-C.0000-0003-1130-5240
Yeh, N.-C.0000-0002-1826-419X
Additional Information:© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). Submitted 29 April 2019. Accepted 14 February 2020. Published 8 May 2020. The authors gratefully acknowledge joint support for this work by the Army Research Office under the MURI program (award #W911NF-16-1-0472), the National Science Foundation under the Physics Frontier Centers program for the Institute for Quantum Information and Matter (IQIM) at the California Institute of Technology (award #1733907), and the Kavli Foundation. Author contributions: N.-C.Y. conceived the ideas and coordinated the research project. C.-C.H. synthesized and characterized the strain-free monolayer graphene, developed architected nanostructures, transferred monolayer graphene and monolayer h-BN to the architected nanostructures for strain engineering, and carried out the SEM and AFM studies. M.L.T. performed the STM/STS studies on strained graphene and analyzed the topographic and spectroscopic data. J.-Q.W. carried out the MD simulations to map out the strain-induced pseudo-magnetic fields and developed a semi-classical model to determine the trajectories of valley-polarized Dirac fermions. N.-C.Y. wrote the paper with contributions from all coauthors. The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.
Group:Institute for Quantum Information and Matter
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-16-1-0472
Kavli FoundationUNSPECIFIED
Issue or Number:19
PubMed Central ID:PMC7209983
Record Number:CaltechAUTHORS:20200508-111719364
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Official Citation:Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene BY C.-C. HSU, M. L. TEAGUE, J.-Q. WANG, N.-C. YEH Science Advances 08 May 2020: Vol. 6, no. 19, eaat9488 DOI: 10.1126/sciadv.aat9488
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103083
Deposited By: George Porter
Deposited On:11 May 2020 14:01
Last Modified:16 Nov 2021 18:18

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