Materials Science Research Lecture

NOTE: Every student or postdoc (any option!) will receive a $5 SmartCash "coffee credit" for each Materials Research lecture attended in person. The credits will be tallied and issued after the last speaker of the term. ***Be sure to put your name on the sign-in sheet so you are counted.

Abstract:

Rhombohedral stacked multilayer graphene is an ideal platform to search for correlated electron phenomena, due to its pair of flat bands touching at zero energy and further tunability by an electric field. Furthermore, its valley-dependent Berry phase at zero energy points to possible topological states when the isospin symmetry is broken by electron correlation. In this talk, I will first show our efforts on the optical spectroscopy study of trilayer graphene/hBN moire superlattice. We observed optical signatures of flat moire band formation and Mott insulator due to band splitting at half-filling. Then I will talk about DC transport measurements of pentalayer graphene without any moire superlattices. We observed a plethora of correlated and topological states including a ferro-valleytronic half-metal, a correlated insulating state and Chern insulator states. Our results point to a new direction of exploring electron correlation and topology in natural 2D crystals where the layer number plays a critical role.​

More about the Speaker:

Long Ju joined the MIT Physics Department as an assistant professor in January 2019. He received his B.S. in Physics in 2009 from Tsinghua University, China, and his Ph.D. in Physics in 2015 from the University of California, Berkeley. He then moved to Cornell University, where he was a Kavli postdoctoral fellow until December 2018.