Browsing by Author "Shi, Wujun"
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- ItemSignatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb2(Weinheim : Wiley-VCH, 2020) Kumar, Nitesh; Yao, Mengyu; Nayak, Jayita; Vergniory, Maia G.; Bannies, Jörn; Wang, Zhijun; Schröter, Niels B.M.; Strocov, Vladimir N.; Müchler, Lukas; Shi, Wujun; Rienks, Emile D.L.; Mañes, J.L.; Shekhar, Chandra; Parkin, Stuart S.P.; Fink, Jörg; Fecher, Gerhard H.; Sun, Yan; Bernevig, B. Andrei; Felser, ClaudiaMultifold degenerate points in the electronic structure of metals lead to exotic behaviors. These range from twofold and fourfold degenerate Weyl and Dirac points, respectively, to sixfold and eightfold degenerate points that are predicted to give rise, under modest magnetic fields or strain, to topological semimetallic behaviors. The present study shows that the nonsymmorphic compound PdSb2 hosts six-component fermions or sextuplets. Using angle-resolved photoemission spectroscopy, crossing points formed by three twofold degenerate parabolic bands are directly observed at the corner of the Brillouin zone. The group theory analysis proves that under weak spin–orbit interaction, a band inversion occurs. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemSingle “Swiss-roll” microelectrode elucidates the critical role of iron substitution in conversion-type oxides(Washington, DC [u.a.] : Assoc., 2022) Liu, Lixiang; Huang, Shaozhuan; Shi, Wujun; Sun, Xiaolei; Pang, Jinbo; Lu, Qiongqiong; Yang, Ye; Xi, Lixia; Deng, Liang; Oswald, Steffen; Yin, Yin; Liu, Lifeng; Ma, Libo; Schmidt, Oliver G.; Shi, Yumeng; Zhang, LinAdvancing the lithium-ion battery technology requires the understanding of electrochemical processes in electrode materials with high resolution, accuracy, and sensitivity. However, most techniques today are limited by their inability to separate the complex signals from slurry-coated composite electrodes. Here, we use a three-dimensional “Swiss-roll” microtubular electrode that is incorporated into a micrometer-sized lithium battery. This on-chip platform combines various in situ characterization techniques and precisely probes the intrinsic electrochemical properties of each active material due to the removal of unnecessary binders and additives. As an example, it helps elucidate the critical role of Fe substitution in a conversion-type NiO electrode by monitoring the evolution of Fe2O3 and solid electrolyte interphase layer. The markedly enhanced electrode performances are therefore explained. Our approach exposes a hitherto unexplored route to tracking the phase, morphology, and electrochemical evolution of electrodes in real time, allowing us to reveal information that is not accessible with bulk-level characterization techniques.