Abstract
We perform ab initio investigations of the bulk and surface band structures of LaSb and LaBi and resolve the existing disagreements about the topological property of LaSb, considering LaBi as a reference. We examine the bulk band structure for band inversion, along with the stability of surface Dirac cones (if any) to time-reversal-preserving perturbations, as a strong diagnostic test for determining the topological character of LaSb, LaBi and LaSb-LaBi multilayer. A detailed ab initio investigation of a multilayer consisting of alternating unit cells of LaSb and LaBi shows the presence of band inversion in the bulk and a massless Dirac cone on the (001) surface, which remains stable under the influence of time-reversal-preserving perturbations, thus confirming the topologically non-trivial nature of the multilayer in which the electronic properties can be tailored as per requirement. A detailed {{mathbb{Z}}}_{2} invariant calculation is performed to arrive at a holistic conclusion.
Highlights
We confirm the robustness of the surface Dirac cone to TR-preserving perturbations, establishing the topologically non-trivial properties of the multilayer, which can potentially be used for device applications by chemical substitution and/or alteration of the stacking sequence of multilayer
This kind of topologically protected heterostructure, with possible extreme magnetoresistive properties co-existing with topologically non-trivial band structure, provides us with an avenue to design new materials with novel functionalities that can be engineered in the laboratory
A 20 × 20 × 20 k-mesh is used for the whole Brillouin zone
Summary
Received: 5 June 2018 Accepted: 26 September 2018 Published: xx xx xxxx heterostructure. A detailed ab initio investigation of a multilayer consisting of alternating unit cells of LaSb and LaBi shows the presence of band inversion in the bulk and a massless Dirac cone on the (001) surface, which remains stable under the influence of time-reversal-preserving perturbations, confirming the topologically non-trivial nature of the multilayer in which the electronic properties can be tailored as per requirement. First-principles calculations of the bulk band structure confirming the presence or absence of band inversion, along with examining the robustness of surface Dirac cones, if any, to TR-preserving perturbations, are needed to ascertain the true topological character of LaSb in comparison to LaBi, which is known as a topologically non-trivial 2 semimetal[38,39]. Presence of bulk band inversion, appearance of an odd number of gapless Dirac cones at the (001) surface, and the robustness of the surface Dirac cones to TR-preserving perturbations establish the topologically non-trivial nature of LaSb-LaBi multilayer heterostructure
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