Anisotropic sub-band splitting mechanisms in strained HgTe: A first principles study

Mercury telluride is a canonical material for realizing topological phases, yet a full understanding of its electronic structure remains challenging due to subtle competing effects. Using first-principles calculations and k\cdot p k ⋅ p modelling, we study its topological phase diagram under strain. We show that linearly k k -dependent higher-order C_4 C 4 strain terms are important for capturing the correct low-energy behaviour. These terms lead to a nontrivial k k -dependence of the sub-band splitting arising from the interplay of strain and bulk inversion asymmetry. This explains the camel-back feature in the tensile regime and supports the emergence of a Weyl semimetal phase under compressive strain.