Abstract: I will present experimental studies on the topological and correlated properties of monolayer TaIrTe4. First, I will discuss a dual quantum spin Hall (QSH) insulator, arising from the interplay between its single-particle topology and density-tuned correlations. At charge neutrality, monolayer TaIrTe4 exhibits QSH insulator behavior, characterized by enhanced nonlocal transport and quantized helical edge conductance. Upon introducing electrons from charge neutrality, TaIrTe4 only shows metallic behavior in a small range of charge densities but quickly goes into a new insulating state. This insulating state could arise from a strong electronic instability near the van Hove singularities, likely leading to a charge density wave. Within this correlated insulating gap, we observe a resurgence of the QSH state. I will also discuss our recent efforts to study this correlated gap using nonlinear Hall responses.
Bio: Dr. Qiong Ma is an assistant professor in the Department of Physics at Boston College. She earned her Bachelor's degree in Applied Physics from the University of Science and Technology of China (USTC) and completed her Ph.D. in Physics at MIT. At Boston College, Qiong's group is developing low-temperature broadband linear and nonlinear spectroscopy, spanning transport, microwave, infrared and optical regimes, to probe quantum geometric properties. Qiong’s research has been recognized with several awards, including the AFOSR and ONR Young Investigator Awards, the Sloan Fellowship, the ACS New Investigator Award, the CIFAR Azrieli Global Scholar Award, the IUPAP Young Scientist Prize for Low Temperature Physics, the NSF Early Career Award.