0428同步年報-2021-全

008 ACTIVITY REPORT 2021 Physics and Materials Science I n the Physics and Materials Science section this year, we report articles covering diverse fascinating topics in basic and applied sciences. A study of the electronic structure of a high- T c cuprate discusses evidence for a quantum- critical scaling and its relation with charge ordering. Studies on monolayer systems continue to provide unexpected results: a strongly correlated charge-density-wave (CDW- Mott) phase was found to show a relatively high CDW ordering temperature with an electronic structure that is robust against doping as well as laser irradiation; a novel phenomenon of a topological proximity effect, occurring between a 2D material and a 3D topological insulator, was identified, thereby opening a route to create quantum spin-Hall systems in monolayer-substrate heterostructures. A multi-orbital system in which not only on-site Coulomb energy U but also Hund’s coupling J H are critical parameters for the ground state was investigated; it revealed clear quasiparticle dispersions as well as doping-dependent low-energy kink structures that provide direct evidence for the role of J H in its electronic structure. A highly innovative study using a miniature floating-gate transistor geometry showed that a partially oxidized InSe surface layer can act as an effective gate that generates a stable electron-storage effect in the underlying InSe channel, with prospective applications for non-volatile memory devices. An in-situ/ operando X-ray absorption spectroscopy study of a double perovskite, Sr 2 CoIrO 6−δ , revealed the role of an uncommon hexavalent Ir 6+ configuration in accelerating electrocatalytic water oxidation; the obtained results make Sr 2 CoIrO 6−δ the most efficient perovskite-based solid-state catalyst for oxygen-evolution reaction. (by Cheng-Maw Cheng and Ashish Atma Chainani)