2026-09-19T17:31:43Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/992892026-06-17T14:45:53Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Pablo Jarillo-Herrero.
Sanchez-Yamagishi, Javier Daniel
Massachusetts Institute of Technology. Department of Physics.
Massachusetts Institute of Technology. Department of Physics
2015-10-14T15:03:31Z
2015-10-14T15:03:31Z
2015
2015
http://hdl.handle.net/1721.1/99289
922889471
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 159-178).
Two-dimensional (2d) layered materials, such as graphene and hexagonal boron nitride (hBN), can be isolated separately and then stacked together to form heterostructures with crystalline interfaces between the layers. In this thesis, I present a series of experiments which explore the quantum transport of electrons in heterostructures made from graphene and hBN. Depending on the relative alignment, or "twist", between the layers, a crystal of hBN can be either a non-perturbing substrate for the graphene, or a method to induce a band gap and superlattice potential for the graphene electrons. In the case of two stacked graphene layers, a relative twist can electronically decouple the layers from each other, despite a tiny 0.34nm interlayer spacing. This twist-dependent physics can be used to realize new electronic states in graphene, especially in the presence of strong magnetic fields and electron-electron interactions. By applying a strong tilted magnetic field to graphene which is decoupled from its hBN substrate, we are able to realize a quantum spin Hall state and measure its electronic properties. An analogous bilayer quantum spin Hall state is also realized in twisted bilayer graphene, by taking advantage of the twist decoupling between the layers and the effects of electron-electron interactions. A different set of experiments explores the competition of a magnetic field with the effects of the superlattice potential which arises when a graphene sheet is nearly aligned to its hBN substrates. The large superlattice potential allows us to study graphene transport in Hofstadter's butterfly-the fractal spectrum for electrons under the simultaneous influence of a lattice and a magnetic field.
by Javier Daniel Sanchez-Yamagishi.
Ph.D.
178 pages
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Physics.
Superlattices and quantum spin Hall states in graphene and hexagonal boron nitride heterostructures
Thesis
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