Physicists at the University of California, Berkeley, have observed a novel Mott state in twisted graphene bilayers at the "magic angle," where superconductivity and other exotic phenomena emerge. The finding, published in the journal Nature, sheds new light on the physics of correlated electrons in two-dimensional materials and could have implications for the development of future quantum technologies.

In twisted graphene bilayers, two layers of graphene are stacked at a slight twist angle. This twist breaks the original crystal symmetry of graphene and gives rise to a variety of new physical properties, including superconductivity and magnetism.

The Mott state is a phase of matter that occurs in materials with strong electron correlations. In a Mott insulator, the electrons are so strongly correlated that they cannot move freely and the material behaves as an insulator. The Mott transition occurs when a material undergoes a phase change from a metallic state to a Mott insulating state as the electron correlations increase.

The researchers at Berkeley observed a novel type of Mott state in twisted graphene bilayers at the magic angle. The Mott state in this system is characterized by a peculiar charge ordering pattern, where the electrons are arranged in a regular pattern of alternating charged and neutral regions.

This novel Mott state is distinct from the Mott states that have been observed in other materials and is a consequence of the unique electronic properties of twisted graphene bilayers. The finding provides a new window into the physics of correlated electrons in two-dimensional materials and could have implications for the development of future quantum technologies, such as high-temperature superconductors and quantum computers.