Pressure Recreates Exotic Quantum Physics in Twisted Graphene

Twisted bilayer graphene (TBG) is renowned for its fascinating quantum properties, but these effects usually appear only when two sheets are twisted at a precise 'magic angle' of about 1.1 degrees. At larger, more experimentally convenient angles, this special behaviour vanishes.

Now, researchers have found a powerful alternative: physical pressure. By systematically applying perpendicular pressure, they can restore the unique 'flatband physics'—where electrons become highly localised and strongly interact—in TBG with much larger twist angles. The pressure enhances the coupling between the graphene layers, mimicking the magic-angle conditions.

In a magnetic field, these pressure-induced flatbands exhibit a tell-tale integer quantum Hall effect, a hallmark of topological phases of matter. This behaviour is confirmed by the material's Hofstadter butterfly spectrum. While the effect has its limits, weakening beyond a critical angle of around 6 degrees, the discovery establishes pressure as a robust tool for engineering correlated and topological states in moiré systems.