Spin-valley locked topological phase transitions in reversible strain-tailoring honeycomb motifs

Abstract

Using an effective low-energy k·p model on the frontier px,y orbitals, we establish a general phase diagram of spin-valley locked band inversion by introducing a mechanical strain field into nonmagnetic honeycomb motifs with robust spin–orbit coupling and intrinsically broken inversion symmetry. Using first-principles calculations, we realize such multiple topological phase transitions in a strained InTe monolayer within experimental reach with the Weyl semimetal as the nontrivial boundary state at two critical strains. The massless Weyl fermions endow the spin and valley Hall effects with ultrafast and dissipationless transport over a broad low-energy window. The valley selective circular dichroism can be regulated by strain-induced band inversion. A crossover between the topologically trivial and nontrivial regimes with sizable bandgaps makes InTe suitable for room-temperature (RT) topological strain-effect transistors. Our work not only demonstrates a fundamental mechanism for exploring tunable topological states and valley physics but also provides a potential platform for realizing many exotic phenomena and RT quantum devices.