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). In particular, I will focus on the prospects of using TIs as an electrically controlled source of spin polarization for all electric spin injection, as well as “spin battery”, “spin capacitor” and “spin memory” in spintronic and quantum information device applications. References:  Yong P. Chen, Proc. SPIE 8373, 83730B (2012)  Y. Xu et al., Nature Physics 10, 956 (2014); Y. Xu et al., arXiv:1511.04597 (2015)  J. Tian et al. Solid State Communications 191, 1 (2014); J.Tian et al., Scientific Reports 5, 14293 (2015)  L. A. Jauregui et al., Scientific Reports 5, 8452 (2015); L. A. Jauregui et al., Nature Nanotechnology, in press, arxiv:1503.00685 (2015)
Yong P. Chen received his BS degree in applied mathematics from Xi’an Jiaotong Univ. (China), his MS degree in mathematics from MIT, and his PhD in Electrical Engineering from Princeton University. He then did a postdoc in physics and nanotechnology at Rice University. Since 2007 he has been on the faculty of both the Department of Physics and Astronomy and School of Electrical & Computer Engineering at Purdue University. He is currently Director of Purdue Quantum Center. Prof. Chen leads an interdisciplinary research group that works on quantum matter and devices involving such systems as graphene & 2D materials, topological insulators, cold atoms & molecules, and explores their applications in electronics, sensors, energy and quantum information. He has published over 160 papers and delivered over 120 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, and Masao Horiba Award.