Physicists capture a strange fractal ‘butterfly’ for the first time

A fractal butterfly pattern produced by an unusual configuration of magnetic fields, first predicted almost 50 years ago, has been seen in detail for the first time in a twisted piece of graphene.

While a physics student in 1976, the computer scientist Douglas Hofstadter predicted that when certain two-dimensional crystals were placed in magnetic fields, their electrons’ energy levels should produce a strange pattern that looks the same no…