Physicists introduce novel mechanisms for electron optics in solid-state systems

Schematic of electron-hole interference: Electron-like (blue) and hole-like (red) coexisting in a dual quantum well say that the system can interfere if it is suitably biased. Sincerely: ETH Zurich / D-PHYS Zilberg Group

Electrons can interfere in the same way as water, acoustic or light waves do. When exploited in solid-state materials, such effects promise novel functionality for electronic devices that integrate elements such as an interferometer, lens, or collimator to control electrons at the Meerco- and nanometer scale. can go. However, so far such effects have been demonstrated mainly in one-dimensional devices, for example in nanotubes, or in two-dimensional Graphene devices under specific conditions. I am writing Physical review xA collaboration including the Department of Physics of Klaus Anselin, Thomas Ihn and Werner Weigcheider in the Laboratory for Solid State Physics and Oleid Zilberg at the Institute for Theoretical Physics, now offer a novel general scenario for realizing electron optics in two dimensions .

The main functional principle of optical interferometers is the interference of monochromatic waves that propagate in the same direction. In such an interferometer, interference can be seen as a periodic oscillation of the transmitted intensity upon varying the wavelength of light. However, the duration of the interference pattern strongly depends on the incident angle of the light, and, as a result, the interference pattern is excluded on average if the light is sent through the interferometer across all possible incident angles simultaneously. The same logic applies to the interference of matter waves described by quantum mechanics, and especially interferometers in which electrons interfere.

As part of his Ph.D. Projects, the experimentalist Matija Karlik and theorist Antonio jtrkalj have investigated the phenomenon of electronic interference in a solid-state system consisting of two-coupled semiconductor layers, InAs and GaSb. They found that the band inversion and hybridization present in this system provide a novel transport mechanism that guarantees non-vanishing interference even at all angles. Through a combination of transport measurements and theoretical modeling, they found that their devices act as Fabry – Perot interferometers, in which electrons and holes form hybrid states and interfere.

The significance of these results goes beyond the typical InAs / GaSb realizations discovered in this work, as the reported mechanism requires only two components of band inversion and hybridization. Therefore, for engineering electron-optical phenomena, new avenues have been opened for many types of materials.

The stacked graphene layers act as a mirror for the electron beam

more information:
Matija Karlik et al., Electron-hole interference in inverted-band semiconductor bilayer, Physical review x (2020). DOI: 10.1103 / PhysRevX.10.031007

ETH Zurich provided by the Department of Physics

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