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CAMP: Valleytronics in two-dimensional crystals

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Di Xiao, Carnegie Mellon University
28 October 2014 from 3:30 PM to 4:30 PM
339 Davey Laboratory
Contact Name
Jun Zhu
Contact Phone
(814) 865-4376
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In many crystals the Bloch bands have degenerate but inequivalent energy extrema in the momentum space, known as valleys. The valley index constitutes a well-defined discrete degree of freedom for low-energy carriers that may be used to encode information.  This has led to the concept of valleytronics, a new type of electronics based on manipulating the valley index of carriers.  In this talk, I will describe a general scheme based on inversion symmetry breaking to control the valley index, which is based on the Berry phase effect of massive Dirac electrons. A number of valley-dependent phenomena, such as valley Hall effect, valley-dependent optical selection rule, spin-valley coupling, optical generation of pure valley current, as well as Berry-phase induced energy splitting of valley excitons will be discussed.