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[PAST EVENT] Physics Colloquium - Victor Galitski
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Victor Galitski (Joint Quantum Institute and Condensed Matter Theory Center, University of Maryland) Title of talk: Strong Correlations Meet Topology in Kondo Insulators
Abstract: Topological states of quantum matter represent a rapidly developing area of research, where a fascinating variety of exotic phenomena occur, ranging from unusual transport properties to fractionalized excitations that may emerge at system’s defects. Of particular recent interest has been the topic of strongly-interacting topological phases, where electronic correlations and topology both play an important role. In this talk, I will review recent theoretical and experimental work on a relatively new class of such interacting topological material system – topological Kondoinsulators, which appear as a result of interplay between strong correlations and spin-orbit interactions. I will start by explaining in simple terms the basics of topological quantum matter, including the by now standard theory of topological band insulators. Then, I will use these concepts to show that the conduction electrons and localized magnetic moments in certain heavy fermion compounds hybridize to give rise to a topological insulating behavior. I will explain key experimental results, which have confirmed our predictions in the Samarium hexaboride heavy fermion compound, where the long-standing puzzle of the residual low-temperature conductivity has been shown to originate from topological surface states. I will also mention several recent theory-experiment collaborative projects that led to the development of a “topological device” and new methods to extend topological behavior in Kondo insulators from a few Kelvin to room temperature. In conclusion, I will discuss a series of recent puzzling experiments, which unexpectedly observed quantum oscillations, typical to a metal, coming from an inert, insulating bulk of Kondo insulators, which may represent a smoking gun of a new fractionalized state of matter.