Excitonic physics in a Dirac quantum dot
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Date
2017-11-27
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Journal ISSN
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Journal Title
Physical Review B
Volume Title
96
Article Title
195434
Publisher
American Physical Society
Abstract
We present a description of vacuum polarization in a circular Dirac quantum dot in two spatial dimensions assuming α - the relative strength of the Coulomb interaction small enough to render an approximation with a single electron (hole) lowest energy level relevant. Applying this approximation, we find that for αc≈1.05 the lowest level is half filled irrespective of the number of flavors that are present. The ground state can be represented as a superposition of particular (even number) excitonic states which constitute an excitonic cloud that evolves in a crossover manner. The ground state is degenerate with an intervalley excitonic state at αc≈1.05, a critical strength, that in our approximation marks a point with single electron and exciton resonances.