Engineering topological phases in the Luttinger semimetal α -Sn

Abstract

α-Sn is well known as a typical Luttinger semimetal with a quadratic band touching at the Γ point. Based on the effective k·p analysis as well as first-principles calculations, we demonstrate that multiple topological phases with a rich diagram, including topological insulator, Dirac semimetal, and Weyl semimetal phases, can be induced and engineered in α-Sn by external strains, magnetic fields, and circularly polarized light (CPL). Intriguingly, not only the conventional type-I Weyl nodes, but also type-II Weyl nodes and double-Weyl nodes can be generated directly from the quadratic semimetal by applying a magnetic field or CPL. Our results apply equally well to other Luttinger semimetals with similar crystal and electronic structures, and thus open an avenue for realizing and engineering multiple topological phases on a versatile platform.

Composite topological nodal lines penetrating the Brillouin zone in orthorhombic AgF2

“…Topological materials have attracted great interest both theoretically and experimentally 1-3 since the proposal of topological insulators (TIs) in 2005. 4 Generally speaking, topological materials can be classified into gapped phases, such as TIs and topological superconductors (TSCs), 1,2 and gapless phases consisting of various topological semimetals (TSMs), such as Weyl semimetals (WSMs), Dirac semimetals(DSMs), [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] nodal-line semimetals (NLSMs), [44][45][46][47][48][49][50][51][52][53] and nodal surface semimetals (NSSMs), [54][55][56][57][58] etc. Symmetries play important roles in the classification of topological phases.…”

Thermal Stability Enhancement in Epitaxial Alpha Tin Films by Strain Engineering

“…However, both the growth of stanene and the following device fabrication require extra care despite of its slightly higher thermal stability. We are interested in bulk α‐Sn films for the reasons that thicker α‐Sn films support more 3D topological phases and benefit device fabrications. In this study, we focus on utilizing the substrate stabilization effect to systematically engineer the thermal stability of α‐Sn films with thicknesses up to thousands of MLs.…”

Hybrid Dispersion Dirac Semimetal and Hybrid Weyl Phases in Luttinger Semimetals: A Dynamical Approach

“…[56] It is important to mention that an external magnetic field can have orbital effects for sufficiently large strength. However, here and in the rest of this paper, we neglect the orbital effects of magnetic field for the sake of simplicity following many works in the literature [42,55,56] and we refer readers to some of the works which explored the effects of magnetic field in Landau levels and quantum oscillations. [62,63] The detailed analysis of the effect of magnetic field (also possible pseudomagnetic fields due to other perturbations) will be left for future studies.…”

“…[27][28][29][30][31][32][33][34][35][36] The coexistence of various Weyl nodes with different charges and/or types is an interesting phenomena that could help toward understanding as well as manipulation of the properties of various Weyl nodes in an equal footing setup. Besides a few works reporting the coexistence of type-I and II Dirac/Weyl nodes, [37][38][39][40][41] there have been also proposals, [42,43] claiming dynamical generation of various Weyl nodes of different types and/or charges in one system. Application of the light is shown to be a powerful method to change the material properties.…”