Superconductivity and strong interactions in a tunable moiré quasicrystal

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Quasicrystals possess unique electronic properties that deviate from Bloch's description, making them complex and less explored than periodic or amorphous materials.
• Existing quasicrystals are often scarce and difficult to engineer, limiting detailed studies of their electronic behavior.

Purpose of the Study:

• To introduce a novel, highly tunable quasicrystal system assembled from readily available periodic components.
• To investigate the electronic properties and emergent phenomena, such as superconductivity, in engineered quasicrystals.

Main Methods:

• Fabrication of a 'moiré quasicrystal' by stacking three layers of graphene with two distinct twist angles, creating incommensurate moiré patterns.
• Tuning the electronic system's chemical potential to transition between periodic-like and strongly quasiperiodic regimes.
• Observing electronic states and phase transitions using transport measurements.

Main Results:

• The moiré quasicrystal exhibits quasiperiodicity on nanometre length scales, tunable from a periodic-like to a strongly quasiperiodic electronic regime.
• A high density of weakly dispersing electronic states was observed in the quasiperiodic regime.
• Superconductivity was detected near a flavour-symmetry-breaking phase transition, highlighting the role of electronic interactions.

Conclusions:

• The engineered moiré quasicrystal provides a versatile platform for studying quasiperiodic electronic systems and interactions.
• This system offers new avenues for exploring quantum phenomena in tunable quasicrystals and related moiré materials.
• Further development of this platform could lead to new quantum materials for investigating strongly interacting quasicrystals.