Direct measurements probe the state of magic-angle twisted graphene

Amid the fanfare around the announced Mott insulating and superconducting states observed in magic-angle twisted bilayer graphene (TBG) in the spring of 2018, the real excitement was around the questions the results left unanswered – what were these states and what might they explain about other systems? By measuring the capacitance of magic-angle TBG Pablo Jarillo-Herrero (who led the research behind the observations announced in 2018) and Ray Ashoori, alongside colleagues at Massachusetts Institute of Technology (MIT) in the US and the National Institute of Materials Science (NIMS) in Japan, have now directly probed the density of states in these systems, as reported in Physical Review Letters. Fast on their heels three other collaborations reporting in three separate letters to Nature have studied these systems with scanning tunnelling microscopy and spectroscopy to provide the first microscopic images of what they look like.