Electrical switching of a moir\'{e} ferroelectric superconductor

TL;DR

This paper demonstrates electrically bistable switching among superconducting, metallic, and insulating states in twisted bilayer graphene with ferroelectric properties, enabling new tunable superconducting electronic devices.

Contribution

It reports the discovery of ferroelectricity in magic-angle twisted bilayer graphene aligned with BN, enabling controllable switching of electronic states.

Findings

Reproducible bistable switching between states using gate voltage.

Ferroelectricity coexists with superconductivity in MATBG.

Potential for highly tunable superconducting electronics.

Abstract

Electrical control of superconductivity is critical for nanoscale superconducting circuits including cryogenic memory elements, superconducting field-effect transistors (FETs), and gate-tunable qubits. Superconducting FETs operate through continuous tuning of carrier density, but there has not yet been a bistable superconducting FET, which could serve as a new type of cryogenic memory element. Recently, unusual ferroelectricity in Bernal-stacked bilayer graphene aligned to its insulating hexagonal boron nitride (BN) gate dielectrics was discovered. Here, we report the observation of ferroelectricity in magic-angle twisted bilayer graphene (MATBG) with aligned BN layers. This ferroelectric behavior coexists alongside the strongly correlated electron system of MATBG without disrupting its correlated insulator or superconducting states. This all-van der Waals platform enables configurable switching between different electronic states of this rich system. To illustrate this new approach, we demonstrate reproducible bistable switching between the superconducting, metallic, and correlated insulator states of MATBG using gate voltage or electric displacement field. These experiments unlock the potential to broadly incorporate this new moir\'{e} ferroelectric superconductor into highly tunable superconducting electronics.