The engineering of Weyl nodes and Dirac-like energy dispersion for topological surface states in Hg[formula omitted]MnxTe under structure and interface inversion asymmetry

Abstract

From Dirac semimetal to Weyl semimetal, a break inversion of time-inversion symmetry (TIS) or inversion symmetry (IS) is required - from this point of view, the possibility of breaking symmetry in HgMnTe alloys is examined in a zincblende structure and the results of numerical calculations are presented in this paper. Low x-Mn (x < 0.04) content in HgMnTe causes a larger strain-induced gap (than in 3D 75-nm strained HgTe) which can be found in the investigated material. As shown, structure inversion asymmetry (SIA) and interface inversion asymmetry (IIA) play a crucial role in the case of Weyl nodes, which should be observed in the investigated material. In both (3D and 2D) systems the SIA is very important as a factor that can be used to modify the obtained energy dispersion for the topological surfaces states (TSS) (in the case of 3D systems) and edge states (in 2D systems). The theoretical investigation presented in this paper based on the eight band kp model allows calculation of the energy spectrum along the entirety of the investigated structures. An external magnetic field is also taken into account. This is the first time that such analysis based on the 8 × 8 kp method has been used to interpenetrate both the surface states and the bulk states for 3D and 2D HgMnTe material under a magnetic field. The obtained results show the entire scope of the energy spectrum and clearly demonstrate that both of the investigated systems are very interesting from application points of view e.g. for terahertz detectors in a magnetic field below 2 T.