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Condensed Matter > Mesoscale and Nanoscale Physics
Title: Two-dimensional topological insulator state in cadmium arsenide thin films
(Submitted on 7 Jan 2023 (v1), last revised 16 Jan 2023 (this version, v2))
Abstract: Two-dimensional topological insulators (2D TIs) are a highly desired quantum phase but few materials have demonstrated clear signatures of a 2D TI state. It has been predicted that 2D TIs can be created from thin films of three-dimensional TIs by reducing the film thickness until the surface states hybridize. Here, we employ this technique to report the first observation of a 2D TI state in epitaxial thin films of cadmium arsenide, a prototype Dirac semimetal in bulk form and a 3D TI in thin films. Using magnetotransport measurements with electrostatic gating, we observe a Landau level spectrum and quantum Hall effect that are in excellent agreement with those of an ideal 2D TI. Specifically, we observe a crossing of the zeroth Landau levels at a critical magnetic field. We show that the film thickness can be used to tune the critical magnetic field. Moreover, a larger change in film thickness causes a transition from a 2D TI to a 2D trivial insulator, just as predicted by theory. The high degree of tunability available in epitaxial cadmium arsenide heterostructures can thus be used to fine-tune the 2D TI, which is essential for future topological devices.
Submission history
From: Susanne Stemmer [view email][v1] Sat, 7 Jan 2023 01:05:12 GMT (8316kb)
[v2] Mon, 16 Jan 2023 22:35:26 GMT (5571kb)
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