Quantum Phases in Topological and Chiral Materials
Dr. Yinong Zhou
Physics and Astronomy
University of California, Irvine
Topological and chiral quantum materials exhibit intriguing electronic, magnetic, and optical properties, holding great promise to shape future electronic and spintronic technologies. In this talk, I will show three different approaches to manipulate quantum phases, based on physics models and density functional theory (DFT) calculations. First, exotic electronic band structures are realized through atomic lattice design, as exemplified by the design of perfectly flat bands based on the line graph theorem. The completely quenched electronic kinetic energy in a flat band magnifies any finite electron-electron interaction, leading to a range of exotic quantum phases, such as ferromagnetism, superconductivity, and Mott insulating state. Specifically, I will present a system with two flat bands of opposite chirality that induces a giant circular dichroism effect and transitions from a flat-band material to a Mott insulator through orbital design. Secondly, topological states are manipulated by applying an external field, which can be either an electric, magnetic, or strain field. As an example, I will demonstrate a physical mechanism to remotely control the topological corner states in a higher-order topological insulator. Thirdly, structural chirality engenders a chiral-induced spin selectivity effect, which enables the harnessing of electron spin to open promising opportunities in spintronics and quantum technologies. Especially, I will showcase the realization of higher-dimensional spin selectivity in chiral crystals for controlling phase transition and spin-flipping processes.
Hosted by Prof. Xiaolong Liu