Refraction of Dirac Fermions across Molecular Graphene Junctions

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Abstract/Contents

Abstract: Graphene has been a subject of great interest in condensed matter physics due to its exotic topological properties. We have used an STM capable of individual atomic manipulation to engineer molecular graphene nanostructures which host relativistic massless Dirac fermions and constitute a fully-tunable electronic system. Motivated by this light-like behavior, our ultimate goal is to create a Veselago lens out of flakes of doped molecular graphene. This work explores the refraction of Dirac fermions across various types of molecular graphene junctions, including neutral-p, neutral-n, n-n, and neutral graphene - 2 dimensional electron system junctions. Principle to our analysis is a new technique combining the traditional quasi-particle interference method used in scanning tunneling microscopy with individual atomic manipulation, which allows us to investigate the scattering of electron wave functions in 2D systems with great precision. Finally, we also explore the possibility of ’tachyonic’ behavior of Dirac fermions as they refract across junctions from areas with higher to lower group velocities. We find significant evidence of refraction of Dirac fermions across various junctions, as well as propose a theoretical explanation for the angles of refraction based off of band structure. We also find evidence of ’tachyonic behavior’ in Dirac fermion refraction.

Author	Yankelevich, Beatriz
Degree granting institution	Stanford University, Program in Engineering Physics
Thesis advisor	Manoharan, Hari
Thesis advisor	Dionne, Jennifer

Subject	graphene
Subject	molecular graphene
Subject	condensed matter physics
Subject	scanning tunneling microscopy
Subject	individual atomic manipulation
Subject	Veselago lens
Subject	Dirac fermions
Subject	refraction
Subject	tachyonic behavior
Genre	Text
Genre	Thesis

Related item	Title 2021 Firestone Medal for Excellence in Undergraduate Research
DOI	https://doi.org/10.25740/jk427px7127
Location	https://purl.stanford.edu/jk427px7127

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License: This work is licensed under a Creative Commons Attribution Non Commercial 4.0 International license (CC BY-NC).

Preferred citation: Yankelevich, Beatriz. (2021). Refraction of Dirac Fermions across Molecular Graphene Junctions. Stanford Digital Repository. Available at: https://purl.stanford.edu/jk427px7127

Undergraduate Theses, Program in Engineering Physics

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