Effect of epitaxial strain on topological properties of LaSb*

Rare-earth mono-pnictides display interesting properties that include extreme magneto resistance and non-trivial topological band structures, yet have simple crystal structure. For instance, LaSb is on the verge of a transition from trivial to non-trivial topological semimetal, LaBi being a non-trivial semi-metal, and LaAs a trivial semimetal. Since these materials can be epitaxially grown on III-V substrates and, therefore, easily integrated to well-known electronic materials, it is imperative to understand the effects of epitaxial strain on their band structures and topological properties. Using DFT with the HSE06 hybrid functional, we study the effects of epitaxial strain on the electronic properties of these rare-earth mono-pnictides. For example, we find that at around 1.5% compressive epitaxial strain there is a band crossing between La d band and Sb p band near the Z point of the BCT Brillouin zone of strained LaSb. This band crossing indicates a topologically non-trivial behavior of LaSb under applied epitaxial strain. These results help understanding the novel transport and topological properties of epitaxially grown strained thin films of these rare earth mono-pnictides.