Electrical switching of a bistable moiré superconductor

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Electrical control of superconductivity is crucial for nanoscale devices like cryogenic memory and superconducting field-effect transistors (FETs).
• Existing superconducting FETs offer continuous tuning but lack bistability, a key feature for memory applications.
• Bistability was recently observed in Bernal-stacked bilayer graphene, suggesting potential in other graphene-based systems.

Purpose of the Study:

• To investigate bistable electrical switching in magic-angle twisted bilayer graphene (MATBG) with aligned boron nitride layers.
• To explore the coexistence of bistability with strongly correlated electron states in MATBG.
• To demonstrate the potential of MATBG as a switchable superconducting material for tunable electronics.

Main Methods:

• Fabrication of van der Waals heterostructures using MATBG and hexagonal boron nitride.
• Electrical transport measurements under varying gate voltages and electric displacement fields.
• Characterization of electronic states including superconducting, metallic, and correlated insulator phases.

Main Results:

• Observation of gate-induced hysteresis and bistable switching in MATBG heterostructures.
• Demonstration of reproducible switching between superconducting, metallic, and correlated insulator states.
• Confirmation that bistability does not disrupt the correlated electron system or superconductivity in MATBG.

Conclusions:

• MATBG with aligned boron nitride exhibits tunable bistable behavior, distinct from continuous tuning in traditional superconducting FETs.
• This all-van der Waals platform allows configurable switching between multiple electronic states.
• The findings pave the way for incorporating switchable moiré superconductors into advanced cryogenic memory and tunable superconducting electronics.