Quantum Phase Transitions in Graphene Coupled to a Twisted WSe2 Moiré Ferroelectricity

Abstract

Sublattice symmetry in graphene governs its Dirac semimetal behavior, where electrons exhibit linear dispersion, limiting its potential for technological applications. Here, moiré ferroelectricity in twisted WSe₂ (t-WSe₂) is exploited to break graphene's sublattice symmetry, inducing a metal-to-insulator transition (MIT) near room temperature. The periodic polarization domains in t-WSe₂ imprint an electrostatic potential onto graphene, breaking its sublattice symmetry and leading to the emergence of a local Dirac point, as observed in the transfer characteristics of a t-WSe₂/graphene field-effect transistor. Temperature-dependent transport measurements reveal multiple MIT points at relatively high temperatures, attributed to the room-temperature ferroelectric polarization in t-WSe₂. Furthermore, A distinct metallic phases is identified exhibiting T² and linear-T dependent longitudinal resistance under electrostatic doping, indicative of Fermi-liquid and non-Fermi-liquid metallic behavior, respectively. Finally, finite-size scaling analysis of R_xx near the MIT points indicates continuous quantum phase transitions near room temperature, establishing moiré ferroelectricity as a pathway for engineering quantum electronic phases of monolayer graphene at ambient conditions.

Keywords: Dirac point; metal‐insulator transition; moiré ferroelectricity; quantum phase transitions; sublattice symmetry breaking; twisted WSe2; t‐WSe2/graphene field‐effect transistor.