Researchers Solve Magic Angle Mystery

March 21, 2019

Moiré pattern (Courtesy: Alex Kruchkov).

Exactly a year ago, researchers at MIT reported on observing superconductivity in twisted bilayer graphene – a new experimental platform engineered on two misaligned graphene layers – at "magic angles" near 1.1°. The origin of these angles was a mystery, however. A team at Harvard University has now shown that they appear to be fundamentally connected to quantum Hall wave functions.

Graphene is a flat crystal of carbon just one atom thick. When two such sheets are placed on top of each other with a small angle misalignment, they form a Moiré pattern. More surprisingly still, at the twist angle of 1.1°, the material becomes a superconductor (that is, it can carry currents with no losses) at 1.7 K. This effect disappears at slightly larger or smaller angle twists.

Continue reading "Researchers solve magic angle mystery" by Belle Dumé, Physics World, 25 Mar 2019.

Also read the original article: Grigory Tarnopolsky, Alex J. Kruchkov, and Ashvin Vishwanath, "Origin of Magic Angles in Twisted Bilayer Graphene," Phys. Rev. Lett. 122 (15 March 2019)