First-principles study of electric-field-induced topological phase transition in one-bilayer Bi(111)

摘要

Using first-principles calculations, we found the topological phasetransition induced by electric fields in one-bilayer Bi(111). The bandgapdecreased with increasing electric field strength, and it is closed at 2.1V/{\AA}. For fields exceeding 2.1 V/{\AA}, the bandgap increased withincreasing electric field strength, reaching 0.34 eV at 4.0 V/{\AA}. Wecomputed the $Z_{2}$ invariant that characterizes topological insulator phases.As results, one-bilayer Bi(111) showed a topological phase transition inducedby the electric field, from the topological insulator phase to the trivialinsulator phase through a Dirac semimetal. This topological phase transitioncould be applied to novel devices.