How to Measure and Use "Topology" in Electronic Transport and Devices?
| Date/Time: | Monday, 24 Sep 2018 from 4:10 pm to 5:00 pm |
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| Location: | Phys 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Abstract: Topological phases of matter (ranging from quantum Hall systems to more recently-emerged "topological materials" such as "topological insulators") is a major paradigm and one of the most actively studied subjects in condensed matter physics. Their scientific and technological interests have also extended into other fields ranging from high-energy physics to electronics industries. Topological materials can create condensed matter analogs of Dirac/Weyl/Majorana "fermions" and other exotic particles, and are also considered promising in potential device applications for new ways of energy-efficient information processing, such as spintronics or perhaps even quantum computing [1]. In this talk, I will discuss the meanings and implications of "topology", drawing upon our recent experimental studies of topological insulators (TI). In particular, I will address the questions of how to experimentally measure "topological transport" and possibly use it in spin-based quantum device applications. I will show how TIs can defy our usual intuition about conductors, allowing a conductor cut in half to maintain the same conductance [2]. I will describe two topological transport "fingerprints" we found that are unique to topological insulators --- a "half-integer" quantum Hall effect [2,3] and a "half-integer" Aharonov-Bohm effect [4]. Finally I will show how the unique momentum-space and real-space topologies of the topological insulators can provide efficient ways to electrically generate non-equilibrium spin-polarization [5] and store them for unprecedented long lifetime, promising a "topologically-protected" "spin battery" [6].
References: [1] S. Ornes, "Topological insulators promise computing advances, insights into matter itself", Proc. Nat. Acad. Sci. 113, 10223 (2016); Cheng Zhang et al., "Towards the manipulation of topological states of matter: a perspective from electron transport" (review), Science Bulletin 63, 580 (2018); [2] Yang Xu et al., Nature Physics 10, 956 (2014); [3] Yang Xu et al., Nature Communications 7, 11434 (2016); [4] Luis A. Jauregui et al., Nature Nanotechnology 11, 345 (2016); [5] Jifa Tian et al., Scientific Reports 5, 14293 (2015); [6] J. Tian et al., Science Advances 3, e1602531 (2017)
Bio: Yong P. Chen is a Professor of Physics and Astronomy and Professor of Electrical & Computer Engineering at Purdue University. He also currently serves as the Director of Purdue Quantum Center, and Associate Director of Research for Purdue's Birck Nanotechnology Center. 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 technologies. He has published over 170 papers and delivered over 180 invited talks and seminars on these topics. He was a recipient of Masao Horiba Award, 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 at Rice University. He is a Fellow of American Physical Society.