Unconventional Quantum Phase Transition between a Topological Excitonic Insulator and a Superconductor

Monolayer WTe2 is an correlated insulator that is also charaterized by its nontrivial topology, strong spin-orbit coupling and excitonic pairing. Upon doping with a moderate density of electrons via electrostatic gating, this topological excitonic insulator state is converted into a superconductor. In this talk, I will report the discovery of two distinct types of gate-tuned quantum phase transition in the same monolayer: one in the underdoped regime towards the excitonic insulator state and the other in the overdoped regime. The underdoped quantum phase transition features an unconventional quantum critical point that cannot be described by established theories.