| Brief Bio of the Speaker | Feng Liu is currently a Distinguished and Ivan B. Cutler Professor in the Department of Materials Science and Engineering at University of Utah. His research interests lie in the theoretical modeling and computer simulation, from electronic to atomic and to mesoscopic scales, to study a wide spectrum of physical behavior of materials, with a special focus on surfaces/interfaces, thin films and low-dimensional materials. His best-known work includes theoretical modeling of self-assembly/self-organization of quantum dots and quantum wires in epitaxial growth of strained thin films, prediction of organic two-dimensional topological materials and surface-based topological states, and prediction of many-body quantum states of yin-yang flat bands. He is the recipient of 2023 Davisson-Germer Prize in Atomic or Surface Physics. He is a fellow of American Physical Society. He served as Divisional Associated Editor of Physical Review Letters and he is founding editor-in-chief for Coshare Science. |
Abstract | Two-dimensional topological superconductor (TSC) represents an exotic quantum material with quasiparticle excitation manifesting in dispersive Majorana modes (DMMs) at the boundaries. A domain-wall DMM can arise at the boundary between two TSC domains with opposite Chern numbers or with a π-phase shift in their pairing gap, which can only be tuned by a magnetic field. In this talk, I will introduce the concept of a ferroelectric (FE) TSC, which not only enriches the domain-wall DMMs but also significantly makes them electrically tunable. The π-phase shift of the pairing gap is shown to be attained between two TSC domains of opposite FE polarization, and switchable by reversing FE polarizations. In combination with ferromagnetic (FM) polarization, the domain wall can host helical, doubled chiral, and fused DMMs, which can be transferred into each other by changing the direction of the electrical and/or magnetic field. Furthermore, based on first-principles calculations, we demonstrate α-In2Se3 to be a promising FE TSC candidate in proximity with a FM layer and a superconductor substrate. Also, we predict that room-temperature ferroelectric BA2PbCl4 (BA for benzylammonium), a 2D hybrid organic−inorganic perovskite, exhibits topological nodal-point superconductivity and DMMs on selected edges and ferroelectric domain walls, extending the already rich functionality of hybrid organic−inorganic perovskites to a new territory. We envision that a FE TSC will significantly ease the manipulation of a DMM by electrical field to realize fault-tolerant quantum computation. |
