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

Abstract

Using first-principles calculations, we found the topological phase\ntransition induced by electric fields in one-bilayer Bi(111). The bandgap\ndecreased with increasing electric field strength, and it is closed at 2.1\nV/{\\AA}. For fields exceeding 2.1 V/{\\AA}, the bandgap increased with\nincreasing electric field strength, reaching 0.34 eV at 4.0 V/{\\AA}. We\ncomputed the $Z_{2}$ invariant that characterizes topological insulator phases.\nAs results, one-bilayer Bi(111) showed a topological phase transition induced\nby the electric field, from the topological insulator phase to the trivial\ninsulator phase through a Dirac semimetal. This topological phase transition\ncould be applied to novel devices.\n