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MSE Seminar: “Engineering 2D Quantum Materials with Atomic Precision” (University of California – Berkeley and Lawrence Berkeley National Laboratory)
March 28, 2023 at 10:30 AM - 12:00 PM
Two-dimensional (2D) materials offer a rich platform for studying quantum phenomena, because their properties can be profoundly altered through heterostructure stacking and defect manipulation, while the resulting electronic and magnetic structure can be directly imaged via surface-sensitive probes. I will discuss several examples that highlight the remarkable potential of engineered two-dimensional (2D) materials for exploring novel quantum phases of matter driven by strong correlation and non-trivial topology using scanning tunneling microscopy (STM). I will first discuss our recent work on visualizing and manipulating 1D chiral edge states in a moiré quantum anomalous Hall (QAH) insulator of twisted monolayer-bilayer graphene (tMBLG). Here spectroscopic mapping allows us to directly identify QAH edge states, while combining electrostatic gating and tip-induced doping enables us to create and manipulate QAH edge states on-demand. I will also discuss the interplay between quantum confinement and strong correlation in engineered 1D twin-boundary defects of semiconducting 1H-MoSe2 , which allows direct spectroscopic imaging of spin-charge fractionalization due to the formation of a 1D Tomonaga-Luttinger liquid. I will conclude by providing a glimpse into new avenues of 2D materials engineering involving advanced atomically-precise characterization in the growing field of quantum materials.
Tiancong Zhu
Postdoctoral Fellow, University of California - Berkeley and Lawrence Berkeley National Laboratory
Dr. Tiancong Zhu is a Postdoctoral Scholar at the University of California, Berkeley and Lawrence Berkeley National Lab working in collaboration with Professor Michael. F. Crommie. His research aims to directly visualize novel quantum states and their wavefunctions using scanning tunneling microscopy (STM). Dr. Zhu has a broad research interest in investigating various correlated and topological behaviors that can be engineered in 2D materials and integrated into functional devices. Some of the research topics include Luttinger liquids, Mott insulators, quantum spin liquids, charge density waves, 2D magnets, quantum spin Hall effect, and quantum anomalous Hall effect. Prior to his current position, Dr. Zhu earned his Ph.D. in Physics from the Ohio State University in 2019 under the supervision of Professor Roland K. Kawakami. During his Ph.D., Dr. Zhu conducted a series of studies on spin and magnetism in 2D materials, where he developed the synthesis of several 2D van der Waals magnets with molecular beam epitaxy and performed systematic studies on spin injection, manipulation, and detection in graphene and its heterostructures. Dr. Zhu received his bachelor’s degree in physics from Peking University in China in 2012.