Elemental Topological Dirac Semimetal α‐Sn with High Quantum Mobility
Lê Đức Anh, Kengo Takase, Takahiro Chiba, Yohei Kota, Kosuke Takiguchi, Masaaki Tanaka
Abstract
Abstract α‐Sn provides an ideal avenue to investigate novel topological properties owing to its rich diagram of topological phases and simple elemental material structure. Thus far, however, the realization of high‐quality α‐Sn remains a challenge, which limits the understanding of its quantum transport properties and device applications. Here, epitaxial growth of α‐Sn on InSb (001) with the highest quality thus far is presented. The studied samples exhibit unprecedentedly high quantum mobilities of both the surface state (30 000 cm 2 V −1 s −1 ), which is ten times higher than the previously reported values, and the bulk heavy‐hole state (1800 cm 2 V −1 s −1 ), which is never obtained experimentally. These excellent features allow quantitative characterization of the nontrivial interfacial and bulk band structure of α‐Sn via a thorough investigation of Shubnikov–de Haas oscillations combined with first‐principles calculations. The results firmly identify that α‐Sn grown on InSb (001) is a topological Dirac semimetal (TDS). Furthermore, a crossover from the TDS to a 2D topological insulator and a subsequent phase transition to a trivial insulator when varying the thickness of α‐Sn are demonstrated. This work indicates that α‐Sn is an excellent model system to study novel topological phases and a prominent material candidate for topological devices.