Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 8, 2020 | Accepted Version + Published + Supplemental Material
Journal Article Open

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

Abstract

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.

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.

Attached Files

Published - eaat9488.full.pdf

Accepted Version - 2005.05532.pdf

Supplemental Material - aat9488_SM.pdf

Files

aat9488_SM.pdf
Files (16.8 MB)
Name Size Download all
md5:5aab9dc87ca6d64df798505951ec4d70
1.4 MB Preview Download
md5:2b418d2fb2a2564c0516640030776558
4.9 MB Preview Download
md5:f3fdaad99fb13442b920b43eb6be731c
10.4 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023