Topological phase transition in half-Heusler compounds HfIrX (X = As, Sb, Bi)

•We find topological insulator and Weyl-semimetal in HfIrX (X = As, Sb, Bi).•We control the topological phases transition by the pressure and atoms substitution.•We explained the physical reasons of the topological phases transition.

We studied the lattice constant and atoms substitution tunable topological phase transition in the half-Heusler compounds HfIrX (X = As, Sb, Bi). At the equilibrium cubic crystal structure and excluding SOC, HfIrAs and HfIrBi are topological nontrivial semimetal, while HfIrSb is a trivial topological insulator. This is because that the “internal pressure” lifts the s-type Γ1Γ1 band above p-type Γ5Γ5 bands in HfIrSb. When SOC is included, HfIrAs and HfIrSb become topological insulator, and normal band insulator, respectively, while HfIrBi is still a topological semimetal. When we induce compressive stress in the ab-plane of HfIrBi, it becomes a Weyl semimetal, with eight Weyl-Points (WPS) at (±±Kx, 0, ±±Kz), (0, ±Ky,±±Ky,±Kz), Kx = Ky = 0.023 Å−1, Kz = 0.108 Å−1.

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