Department of Physics

Colloquia speaker and students listening

Physics Department Colloquia & Seminars

Fall 2023 and Spring 2024

Synthesis and Characterization of Novel 2D Dirac/Weyl Materials

Speaker: Dr. Chunhui Chen
Date: Thursday, November 30, 2023
Time: 3:00 P.M. Central Standard Time

Abstract: The discovery of graphene has stimulated enormous interest in two-dimensional (2D) electron gas with linear band structure. 2D Dirac materials possess many intriguing physical properties such as high carrier mobility and zero-energy Landau level for the relativistic dispersion and chiral spin/pseudospin texture. In this talk, we will discuss three new variants of 2D Dirac materials including (1) unpinned 2D Dirac semimetals in α-antimonene1,2, (2) Rashba spin-split 2D Weyl semimetals in α- bismuthene3, and (3) interacting Dirac states in graphene heterostructures4. The results offer new insights to the relativistic behavior of electrons in reduced dimensions. We will review the emergent properties and device applications of relativistic electrons in those 2D Dirac/Weyl semimetals, especially, cloning of Dirac fermions, Moiré flat bands, and spin/valley separators.


[1] Lu et al., Nat. Commun. 13:4603 (2022)

[2] Kowalczyk et al., ACS Nano 14, 1888 (2020)

[3] Lu et al., arXiv:2303.02971(2023)

[4] Lu et al., Advanced Materials 2200625 (2022)

About the speaker: Guang Bian is an associate professor at the department of physics and astronomy, University of Missouri, Columbia. After receiving his Ph.D. at University of Illinois at Urbana- Champaign in 2013, he was a postdoctoral fellow at Princeton University and he joined University of Missouri as an assistant professor in 2016. Dr. Bian has extensive experience in molecular beam epitaxy (MBE) fabrication and spectroscopic characterization of low-dimensional quantum systems and novel topological/functional materials. Dr. Bian’s research work has been recognized by “President's Early Career Award”, University of Missouri (2019), “Aladdin Lamp Award”, Synchrotron Radiation Center, Wisconsin (2010), and “Gordon and Betty Moore Foundation Experimental Physics Investigator” (2023).


The Mystery of the Matter and Antimatter Asymmetry

Speaker: Dr. Chunhui Chen
Date: Thursday, November 9, 2023
Time: 4:00 P.M. Central Standard Time
Location: Currens Hall 205

Abstract: In modern physics, every type of particle (matter) is accompanied by an antiparticle (antimatter) of equal mass but possessing opposite electric charge, parity, and time properties. Both matter and antimatter were generated in equal quantities during the Big Bang, which marked the birth of our Universe. However, while matter is abundant in the cosmos today, antimatter has become exceedingly elusive. The profound enigma of how antimatter disappeared during the Universe's evolution, known as the Matter and Antimatter Asymmetry problem, has perplexed scientists for years. To address this mystery, physicists are employing SuperKEKB, the world's brightest particle collider, located at The High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. This facility enables physicists to create a controlled physical system with an equal quantity of matter and antimatter, facilitating the study of their properties and interactions. This research aims to elucidate CP violation, a fundamental principle that may offer insights into the disappearance of antimatter in our Universe. In this presentation, I will provide an overview of the historical context, the physics involved, and the latest findings pertaining to the Matter and Antimatter Asymmetry, as discovered through our experiments. The talk will be tailored to a general audience and will avoid delving into excessive technical details, ensuring that the content remains accessible to undergraduate physics students.

About the speaker: Professor Chunhui Chen is an experimental particle physicist affiliated with Iowa State University. Throughout his career, he has conduct research at large international experiments at Fermilab, the Stanford Linear Accelerator Center, the European Organization for Nuclear Research (CERN), and The High Energy Accelerator Research Organization (KEK). At present, Professor Chen is actively engaged in the Belle II experiment, located at KEK in Tsukuba, Japan. His current research is primarily focused on unraveling the mystery surrounding the asymmetry between matter and antimatter. More information about Professor Chen’s research can be found at: