Fabrication of Nanoscale Aharonov-bohm Rings of Bismuth Selenide

Open Access
Author:
Hopper, David Allen
Area of Honors:
Physics
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Nitin Samarth, Thesis Supervisor
  • Richard Wallace Robinett, Honors Advisor
Keywords:
  • Topological Insulators
  • Nanofabrication
  • Mechanical Exfoliation
  • Bismuth Selenide
Abstract:
Topological insulators are a fascinating new classification of materials that exhibit novel physics such as image magnetic monopoles, Majorana fermions, and the quantum anomalous Hall effect. The hallmark of a topological insulator is that the material is a bulk insulator, but there exist conducting surface states. The surface states manifest due to large spin orbit coupling and band inversion in most materials. Recent studies of Bismuth Selenide (Bi2Se3) have shown unexpected oscillations in magneto-resistance measurements. Our group observed Aharonov- Bohm oscillations in epitaxial Bi2Se3, caused by Aharonov-Bohm orbits around triangular terraces in the epitaxial film. The goal of this thesis was to create a system that could study how a single triangular terrace would behave, by creating a nanoscale Aharaonov-Bohm ring out of exfoliated Bi2Se3. The exfoliation and identification process are outlined in detail. Due to interference effects of thin films and light, a correlation between the color and the thickness has been determined. The rings were fabricated using a Focused Ion Beam and limits on the scale of the fabrication have been determined.