Spring 2022

A CMU-PITT Colloquium 

Abstract: Moire heterostructure is an exciting class of highly-tunable platforms hosting various types of strongly-correlated physics. In this talk, I will present two different emergent quantum phenomena arising in this platform: (i) Correlated insulator and correlated semimetal in twisted graphene layers, and (ii) fractional Chern insulators and emergent quantum electrodynamics in Moire materials under magnetic field.

The first part of the talk covers the rich physics of twisted graphene layers originated from multi-flavored...

A CMU-Pitt Colloquium

Abstract: Atomically thin Van der Waals materials have emerged as a highly versatile platform to advance our understanding of quantum matter driven by strong electron correlations. Recent experimental breakthroughs in stabilizing few-layered graphene structures with a “magic” relative twist between layers has led to the discovery of a wide variety of correlated states ranging from magnetism to superconductivity. Despite compelling experimental evidence for unconventional superconductivity, the glue which binds electrons into Cooper...

A CMU-PITT Colloquium

Abstract: Electron microscopy is transforming the physical sciences. Aided by a new generation of direct imaging detectors, cryo-electron microscopy won the 2017 Nobel Prize in Chemistry for advancements in visualization of biomolecules.  To go beyond traditional electron microscopy, new detectors must also be developed for the diffraction imaging; here, the scattered electron beam encodes a wealth of information about the structure, chemistry, electrical, optical, and magnetic properties of matter. During my PhD, I co-invented the...

A Pitt/CMU Colloquium

Abstract: The extraordinary advances in quantum control of matter and light have been transformative for atomic and molecular precision measurements enabling probes of the most basic laws of Nature to gain a fundamental understanding of the physical Universe. Exceptional versatility, inventiveness, and rapid development of precision experiments supported by continuous technological advances and improved atomic and molecular theory led to rapid development of many avenues to explore new physics. I will give an overview of atomic and...

A Pitt/CMU Colloquium

Abstract: Superconductivity is a collective state in which many fermions pair up to give rise to a zero-resistance electron transport regime. The majority of superconductors are well described by a Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity in which a weak momentum space attraction between fermions forms bound Cooper pairs separated in real space. When attraction becomes strong the Cooper pair size shrinks until it effectively forms a diatomic Bose molecule that can, in turn, undergo Bose-Einstein condensation (BEC). A solid-...

A Pitt/CMU Colloquium

Abstract: Plasmons, the self-sustained collective density modes in metals, form an integral part of the description of interacting electronic systems. Conventionally, plasmon dynamics are often dominated by the density and effective mass of carriers in its host metal. We will discuss how this description falls short in topological materials where the intricate twisting of wavefunctions (i.e. Bloch band quantum geometry) lead to a new class of plasmonic collective modes. These "topological plasmons" possess a wealth of exotic properties...

A Pitt Chem Seminar

Abstract: Quantum materials, as an emerging term, include materials with electronic or magnetic properties originating from nontrivial quantum mechanics, such as superconductors, topological materials, quantum spin liquids etc. Such materials are attractive not only due to their exotic quantum physics, but also vast potential applications and corresponding economic benefits. Thus, it is necessary for the communities of solid-state chemistry, condensed matter physics and materials science to explore novel quantum materials and...

A Pitt Chem Seminar

Abstract: Since the discovery of conducting polymers, organic materials have promised great applications in energy conversion, electronics, and chemical sensing. Synthetic chemistry has been rapidly advancing the development of organic materials with desired properties and functions. At the core of the research is understanding the structure-property relationships and developing new chemical structures and synthetic methods. In this talk, I will present several design principles of functional organic materials based on the concept of...