High-pressure induced Weyl semimetal phase in 2D Tellurium

Relativistic Weyl fermion quasiparticles in Weyl semimetal bring the electron’s chirality degree of freedom into the electrical transport and give rise to exotic phenomena. A topological phase transition from a topological trivial phase to a topological non-trivial phase offers a route to control electronic devices through its topological properties. Here, we report the Weyl semimetal phase in hydrothermally grown two-dimensional Tellurium (2D Te) induced by high hydrostatic pressure (up to 2.47 GPa). The unique chiral crystal structure gives rise to chiral fermions with different topological chiral charges ( C = − 1 , + 1 , a n d − 2 ). The highly tunable chemical potential in 2D Te provides comprehensive information for understanding the pressure-dependent electron band structure. The pressure-induced insulator-to-metal transition, two-carrier transport, and the non-trivial π Berry phase shift in quantum oscillations are observed in the 2D Te Weyl semimetal phase. Our work demonstrates the pressure-induced bandgap closing in the inversion asymmetric narrow bandgap semiconductor 2D Te. Driving a quantum material from trivial to non-trivial topological phase can be engineered, for instance, by an applied external field but understanding the physics of the transition can be complex. Here, the authors report a pressure-induced topological phase transition from a semiconductor to a Weyl semimetal phase in 2D Te, and investigate the underlying dynamics using a range of magneto-transport techniques.