Abstract:

　　Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy. A tunable Mott insulator, where the competition between the Coulomb interaction and the kinetic energy can be varied in situ, can provide an invaluable model system for the study of Mott physics. In this talk, I will discuss a general route to engineer strongly correlated physics in two-dimensional moiré superlattices, and show the experimental realization of a tunable Mott insulator in the ABC stacked trilayer graphene (TLG)/hBN moiré superlattice. The moiré superlattice in TLG/hBN heterostructures leads to narrow electronic minibands and allows for the observation of gate-tunable Mott insulator states at 1/4 and 1/2 fillings. Interesting signatures of superconductivity are observed at low temperature near the 1/4 filling Mott insulating state in the TLG/hBN heterostructures. A topological Chern insulator with Chern number C = 2 and ferromagnetism are experimentally observed in the non-trivial band in trilayer graphene system, which makes it possible to study Mott, superconductivity and topological physics in one system.

Biosketch：

　　Guorui Chen, a postdoctoral fellow at the University of California, Berkeley. In 2010, he graduated from the School of Physics and Microelectronics of Shandong University. In 2016, he graduated from the Physics Department of Fudan University and stayed as a postdoctoral fellow. From 2017 to now, he is a postdoctoral fellow in the Department of Physics at the University of California, Berkeley. His research interests are mainly in high-quality two-dimensional materials and their van der Waals heterostructures, especially in quantum transport of the strong correlation and topological effects of graphene moire systems. In recent years, more than ten articles have been published in journals such as Nature, Nature Physics, Nature Materials, PRL and Nano Letters, and have been cited more than 1,000 times.