Solid-State and Nano Seminar
What are topological insulators good for?
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Topological insulators (TI) have recently attracted a lot of interests in both solid state physics and nanoelectronics community. These materials are semiconductors (band insulators) in the bulk (with "negative bandgap"), but have "topologically protected" conducting surfaces with spin-polarized, graphene-like Dirac electrons, promising a large number of exotic electronic and optical properties. But what are these materials really good for, and what may be some of the first practical device applications of topological insulators? In this talk, I will review the key electronic properties and device potentials of TIs. I will present our recent experimental demonstration of the most intrinsic TI so far (with no measureable bulk conduction "“ realizing a 3D material whose conductance does not depend on thickness and comes only from its surface, some even at room temperature), along with some of the most salient electronic transport signatures of TI's spin-helical, Dirac fermion "topological surface states", such as the "half-integer quantum Hall effect", and the "spin-momentum locking" detected by direct electrical injection and detection of spin-polarized surface current. I will discuss some examples of potential devices applications of TIs in spintronics and energy conversion (eg. thermoelectrics).
Yong P. Chen is Associate Professor of Physics and Astronomy and Associate Professor of Electrical & Computer Engineering at Purdue University. He leads an interdisciplinary research group that works on quantum matter and devices involving such systems as graphene & 2D materials, topological insulators, and cold atoms & molecules, and explores their applications in electronics, sensors, energy and quantum information. He has published over 140 papers and delivered over 100 invited talks and seminars on these topics. He was a recipient of NSF CAREER Award, DOD DTRA Young Investigator Award, IBM Faculty Award and Purdue University's Miller Family Professorship in Nanoscience and University Faculty Scholar Award. He received an MSc degree in mathematics from MIT, a PhD in Electrical Engineering from Princeton University and did a postdoc in physics and nanotechnology at Rice University.