Colloquium: Qiong Ma (Boston College)

Abstract:  Electricity, the foundation of modern technology, is carried by electrons in solids. Understanding how electrons behave where they interact with Avogadro’s number of surrounding particles has been a central pursuit in condensed matter physics.  From early band theory, which classified insulators, metals, and semiconductors, to the exploration of quantum materials hosting exotic emergent electronic phenomena, the field has continually advanced. Research on these quantum materials has been revealing a diverse range of phenomena, including topological phases, hydrodynamic electron transport, unconventional superconductivity, and correlated insulating states, all of which open new avenues for novel electronic functionalities. In this talk, I will introduce a new monolayer quantum material that combines nontrivial topology with a high electronic density of states, providing an intrinsic and highly controllable platform for emergent collective behaviors. I will present a series of unusual electronic phenomena observed in this system, including dual quantum spin Hall insulating states, an electronically driven superlattice memory, and the realization of a Hall diode.