Charge density wave phase transition on the surface of electrostatically doped multilayer graphene

Abstract

We demonstrate that the charge density wave (CDW) phase transition occurs on the surface of electronically doped multilayer graphene when the Fermi level approaches the M points (also known as van Hove singularities where the density of states diverge) in the Brillouin zone of the graphene band structure. The occurrence of such CDW phase transitions is supported by both the electrical transport measurement and optical measurements in electrostatically doped multilayer graphene. The CDW transition is accompanied with the sudden change of graphene channel resistance at Tm = 100 K, as well as the splitting of Raman G peak (1580 cm−1). The splitting of Raman G peak indicates the lifting of in-plane optical phonon branch degeneracy, and the non-degenerate phonon branches are correlated to the lattice reconstructions of graphene—the CDW phase transition.