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arXiv · 2302.11281

Velocity and confinement of edge plasmons in HgTe-based 2D topological insulators

Alexandre Gourmelon·Elric Frigerio·Hiroshi Kamata·Lukas Lunczer·Anne Denis·Pascal Morfin·Michael Rosticher·Jean-Marc Berroir·Gwendal Fève·Bernard Plaçais·Hartmut Buhmann·Laurens W. Molenkamp·Erwann Bocquillon
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Abstract

High-frequency transport in the edge states of the quantum spin Hall (QSH) effect has to date rarely been explored, though it could cast light on the scattering mechanisms taking place therein. We here report on the measurement of the plasmon velocity in topological HgTe quantum wells both in the QSH and quantum Hall (QH) regimes, using harmonic GHz excitations and phase-resolved detection. We observe low plasmon velocities corresponding to large transverse widths, which we ascribe to the prominent influence of charge puddles forming in the vicinity of edge channels. Together with other recent works, it suggests that puddles play an essential role in the edge state physics and probably constitute a main hurdle on the way to clean and robust edge transport.

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Alexandre Gourmelon, Elric Frigerio, Hiroshi Kamata, Lukas Lunczer, Anne Denis, Pascal Morfin, Michael Rosticher, Jean-Marc Berroir, Gwendal Fève, Bernard Plaçais, Hartmut Buhmann, Laurens W. Molenkamp, Erwann Bocquillon. 2023-02-22. Velocity and confinement of edge plasmons in HgTe-based 2D topological insulators. https://doi.org/10.1103/physrevb.108.035405

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