Strain-Engineered Thermophysical Properties ranging from Band-Insulating to Topological Insulating Phases in β-Antimonene

Employing strain may lead to unusual modifications in the material’s properties. Low-dimensional materials having large mechanical strength are well suited for strain engineering. In our work, we present the structural, electronic, thermal, and vibrational characteristics along with the phonon and carrier dynamics of β-Sb elemental monolayers for achieving the band-insulating phase at no strain and topological insulating phase at ∼15% biaxial strain. The weakened π and σ bonds under strain, leading to anharmonicity in the system. It is further reflected by the drop in lattice thermal conductivity (κ_l) from 4.5 to 3.1 W m⁻¹ K⁻¹ at ~15% strain, i.e., in the topological phase. Helical edge states at 15% strain and meeting the Z₂ invariant criterion confirm the non-trivial topological state. Here we noticed the significant contribution of the out-of-plane A_1g vibrational mode in the topological phase compared with the band-insulating phase. Importantly, the dominance of the out-of-plane optical modes contributes significantly to the topological phase along the band edges, which is primarily due to the reduced buckling height under strain. This work emphasizes the microscopic origin of the onset of the topological phase in strained β-Sb monolayers and provides strain-engineered structure–property correlations for better insights.