Twist angle physics in graphene based van der Waals heterostructures
Author(s)Luo, Yuanhong, Ph. D. Massachusetts Institute of Technology
Massachusetts Institute of Technology. Department of Physics.
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In this thesis, I present my experimental work on twisted bilayer graphene, a van der Waals heterostructure consisting of two graphene sheets stack on top of each other. In particular, the twist angle is a new degree of freedom in this system, and has an important effect in the determination of its transport properties. The work presented will explore the twist-dependent physics in two regimes: the large twist angle and small twist angle regimes. In the large-twist angle limit, the two sheets have little interlayer interactions and are strongly decoupled, allowing us to put independent quantum Hall edge modes in both layers. We study the edge state interactions in this system, culminating in the formation of a quantum spin Hall state in twisted bilayer graphene. In the small twist angle limit, interlayer interactions are strong and the layers are strongly hybridized. Additionally, a new long-range moiré phenomenon emerges, and we study the effects of the interplay between moiré physics and interlayer interactions on its transport properties.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged student-submitted from PDF version of thesis.Includes bibliographical references (pages 121-131).
DepartmentMassachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology