Screening properties and plasmons of Hg(Cd)Te quantum wells

Abstract

Under certain conditions, Hg(Cd)Te quantum wells (QWs) are known to realize a time-reversal symmetric, two-dimensional topological insulator phase. Its low-energy excitations are well-described by the phenomenological Bernevig-Hughes-Zhang (BHZ) model that interpolates between Schrödinger and Dirac fermion physics. We study the polarization function of this model in random phase approximation (RPA) in the intrinsic limit and at finite doping. While the polarization properties in RPA of Dirac and Schrödinger particles are two comprehensively studied problems, our analysis of the BHZ model bridges the gap between these two limits, shedding light on systems with intermediate properties. We gain insight into the screening properties of the system and on its characteristic plasma oscillations. Interestingly, we discover two different kinds of plasmons that are related to the presence of intra- and interband excitations. Observable signatures of these plasmons are carefully analyzed in a variety of distinct parameter regimes, including the experimentally relevant ones for Hg(Cd)Te QWs. We conclude that the discovered plasmons are observable by Raman or electron loss spectroscopy.

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Cited by in corpus (8)

• Quasi-flat plasmonic bands in twisted bilayer graphene
• Plasmonics in topological insulators: Spin-charge separation, the influence of the inversion layer, and phonon-plasmon coupling
• Topological edge states of Kekulé-type photonic crystals induced by a synchronized rotation of unit cells
• Quantum capacitance of an HgTe quantum well as an indicator of the topological phase
• Anomalous Spin Response and Virtual-Carrier-Mediated Magnetism in a Topological Insulator
• Interaction Induced Magnetotransport in a 2D Dirac-Heavy Hole Hybrid Band System
• Universal absorption of two-dimensional systems
• Interband plasmons due to Mexican hat dispersion in two-dimensional materials with inverted bands