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theses

This dissertation seeks to understand the novel physical properties of a new class of materials called topological insulators (TIs) from an experimental standpoint, and, in particular, is concerned with electrical transport properties of atomic scale thin films structures of the TI Bi2Se3 grown by the molecular beam epitaxy technique. We first begin by reviewing the nascent field of TIs, which will act to motivate the work. This will be followed by a thorough introduction to the many aspects concerning the synthesis of thin film TIs by the atomically precise technique of molecular beam epitaxy. This is then followed by a brief introduction to, and the details of electrical transport, which is the main experimental technique used in this work. In the remaining chapters we apply these techniques to understand the fundamental properties of this new class of materials. As a point of necessity, we first discuss the effects that exposure to atmospheric gases have on the transport properties of Bi2Se3. Following this, we examine the properties of (Bi1-xInx)2Se3, which transitions from a topological insulator (x = 0) into a topologically trivial band insulator (x = 1) through three quantum critical points. We then detail two studies that probe the intrinsic properties of the topological surface states. The first study deals with the emergence of decoupled topological surface states when the metallic bulk state is suppressed. The second study presents a new phase called an inverse TI, whose electronic properties can be engineered chemically, which is found to allow control over the coupling between the topological surface states. This will lead into the final work, which is concerned with understanding the global properties of transport measurements on TIs.

ETD_5887

Ph.D.

Includes bibliographical references

by Matthew J. Brahlek

doi:10.7282/T3TM78KB

ETD doctoral

The author owns the copyright to this work.