Topological Dirac semimetal phases in InSb/$\alpha$-Sn semiconductor superlattices

TL;DR

This paper theoretically demonstrates the coexistence of Dirac semimetal and topological insulator phases in InSb/$ ext{α}$-Sn semiconductor superlattices, highlighting the role of interface design and electrostatic fields in inducing topological phases.

Contribution

It introduces a novel approach to realize coexisting topological phases in conventional semiconductor superlattices through interface engineering and electrostatic field manipulation.

Findings

Dirac semimetal phase with Dirac nodes near the Γ point.

Observation of surface states and Fermi arcs.

Identification of a 2D topological insulator phase with a large band gap.

Abstract

We demonstrate theoretically the coexistence of Dirac semimetal and topological insulator phases in InSb/$\alpha$-Sn conventional semiconductor superlattices, based on advanced first-principles calculations combined with low-energy $k\cdot p$ theory. By proper interfaces designing, a large interface polarization emerges when the growth direction is chosen along {[}111{]}. Such an intrinsic polarized electrostatic field reduces band gap largely and invert the band structure finally, leading to emerge of the topological Dirac semimetal phase with a pair of Dirac nodes appearing along the (111) crystallographic direction near the $\Gamma$ point. The surface states and Fermi arc are clearly observed in (100) projected surface. In addition, we also find a two-dimensional topological insulator phase with large nontrivial band gap approaching 70 meV, which make it possible to observe the quantum spin Hall effect at room temperature. Our proposal paves a way to realize topological nontrivial phases coexisted in conventional semiconductor superlattices by proper interface designing.