So-Young Pi

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Controlling the properties of materials by driving them out of equilibrium is an exciting prospect that has only recently begun to be explored. In this Letter we give a striking theoretical example of such materials design: a tunable gap in monolayer graphene is generated by exciting a particular optical phonon. We show that the system reaches a steady(More)
We show that quasiparticle excitations with irrational charge and irrational exchange statistics exist in tight-binding systems described, in the continuum approximation, by the Dirac equation in (2+1)-dimensional space and time. These excitations can be deconfined at zero temperature, but when they are, the charge rerationalizes to the value 1/2 and the(More)
We show that in a large class of physically interesting systems the mass-generation phenomenon can be understood in terms of topological structures, without requiring a detailed knowledge of the underlying dynamics. This is first demonstrated by showing that Schwinger's mechanism for mass generation relies on topological structures of a two-dimensional(More)
Fermion-number fractionalization without breaking the time-reversal symmetry was recently demonstrated for a field theory in ͑2+1͒-dimensional space and time that describes the couplings between massive Dirac fermions, a complex-valued Higgs field carrying an axial gauge charge of 2, and a U͑1͒ axial gauge field. Charge fractionalization occurs whenever the(More)