Quantum confinement effects in the topological Dirac semimetal α-Sn on InSb(111)

Abstract

The diamond-like allotrope of Sn (alpha-Sn) is tantalizing, being an elemental semimetal that hosts a range of topological properties. Despite the intriguing potential of this quantum material, a detailed understanding of its nontrivial electronic structure remains relatively poor. Here, we prepared alpha-Sn in a well-defined quantum phase (i.e., topological Dirac semimetal) by applying a compressive strain via epitaxial growth on the (111) surface of an InSb substrate. We varied the thickness of the alpha-Sn epilayer to single out the emergence of quantum confinement effects. Our electrical investigation suggests a thickness-dependent modification of transport mechanisms. These results are complemented by the measurement of the cyclotron resonance, which manifests the role of quantum confinement in defining the effective mass of topological Dirac fermions as bulk carriers. Our results contribute to deepening the knowledge of the alpha-Sn electronic properties. This is pivotal to increase the future applicability of Sn-based architectures into beyond-stateof-the-art devices.