Fernandes part of a collaboration that identified electronic nematicity in a twisted system
Two side by side images of graphene
Two 200 nm-wide spectroscopy images of a sample of twisted double bilayer graphene. The left depicts the triangle lattice of the moiré material, which has three-fold symmetry and can be rotated 120 degrees any direction without changing the image. The second image was taken at a different energy level and can now only be rotated 180 degrees. The emergence of stripes reflects this broken rotational symmetry and indicates a nematic phase.

Electronic nematic order is a unique state of matter observed in several quantum materials, including some that display unusual superconductivity -- i.e. the ability to conduct electricity without dissipation. Professor Rafael Fernandes of the School of Physics and Astronomy is part of a joint theoretical-experimental research collaboration that found such an electronic nematic phase in a system built by twisting two bilayers of graphene with respect to each other by a small angle. This result sheds new light not only on the universal properties of the recently discovered twisted graphitic systems, but more broadly on the collective behavior of electrons subjected to strong interactions.

The full story can be read here: https://quantum.columbia.edu/news/nematicity-new-piece-phase-diagram-puzzle.

The paper can be accessed at: https://www.nature.com/articles/s41567-021-01438-2.

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