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arXiv · 1309.6083

Plasmons due to the interplay of Dirac and Schrödinger fermions

Stefan Juergens·Paolo Michetti·Björn Trauzettel
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Abstract

We study the interplay between Dirac and Schrödinger fermions in the polarization properties of a two-dimensional electron gas (2DEG). Specifically, we analyze the low-energy sector of narrow-gap semiconductors described by a two-band Kane model. In the context of quantum spin Hall insulators, particularly, in Hg(Cd)Te quantum wells, this model is named Bernevig-Hughes-Zhang model. Interestingly, it describes electrons with intermediate properties between Dirac and Schrödinger fermions. We calculate the dynamical dielectric function of such a model at zero temperature within random phase approximation. Surprisingly, plasmon resonances are found in the intrinsic (undoped) limit, whereas they are absent - in that limit - in graphene as well as ordinary 2DEGs. Additionally, we demonstrate that the optical conductivity offers a quantitative way to identify the topological phase of Hg(Cd)Te quantum wells from a bulk measurement.

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Stefan Juergens, Paolo Michetti, Björn Trauzettel. 2014-01-23. Plasmons due to the interplay of Dirac and Schrödinger fermions. https://arxiv.org/abs/1309.6083

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