Hofstadter's Butterfly

Hofstadter Butterfly in graphene superlatticesWhen graphene is placed in contact with hexagonal boron, a moire pattern develops with long range order, which in turn looks like a crystal field to the free electrons in the graphene layer.  We were able to exploit the large length-scale of the moire superlattice  (~15 nm) to look for the long predicted Hofstadter butterfly energy spectrum, expected to emerge under simultaneous application of both a magnetic field and  a spatially varying electrostatic field.  Read more about our exciting resuls in the magazine Nature.  [link]