Emerging flat bands in large-angle twisted bi-layer graphene under pressure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Magic-angle twisted bi-layer graphene (TBG) exhibits exotic properties like unconventional superconductivity and correlated insulation.
• These phenomena are typically observed at small twist angles (<1.1°), which are challenging to fabricate precisely.

Purpose of the Study:

• To investigate the electronic properties of large-angle TBG under applied pressure.
• To explore the potential for inducing flat bands and related exotic properties in large-angle TBG.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Electronic properties of large-angle TBG were simulated under varying pressure conditions.

Main Results:

• Large-angle TBG can exhibit flat bands near the Fermi level when subjected to pressure.
• Applied pressure leads to a monotonic decrease in Fermi velocity for large twisted angles (e.g., 21.8°).
• Pressure-induced flat bands in large-angle TBG may lead to superconductivity, similar to small-angle TBG at ambient pressure.

Conclusions:

• Applying pressure is a viable strategy for flat-band engineering in large-angle TBG.
• This work supports further investigations into pressure-tuned electronic properties of twisted bi-layer graphene for novel quantum phenomena.