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New website: weichichiu.com
Source: Figure panel, C. Hong et al., Nature 617, 493–498 (2023).
Copyright: © 2023 The Authors, under exclusive licence to Springer Nature Limited.
Anomalous Intense Coherent Secondary Photoemission from a Perovskite Oxide
Anomalous Intense Coherent Secondary Photoemission from a Perovskite Oxide
Caiyun Hong, Wenjun Zou, Pengxu Ran, K. Tanaka, M. Matzelle, Wei-Chi Chiu, R. S. Markiewicz, B. Barbiellini, Changxi Zheng, Sheng Li, Arun Bansil, and Rui-Hua He
Our theory–experiment collaboration uncovered unusually intense, coherent secondary photoemission from a reconstructed SrTiO3 surface. The material produces discrete secondary-emission peaks despite its positive electron affinity, with enhanced coherence at low temperatures. This work connects microscopic surface electronic structure and emission pathways to measurable beam properties, identifying perovskite oxides as a platform for coherent electron sources.
See also: M. Matzelle†, Wei-Chi Chiu†, Caiyun Hong et al., Recycling failed photoelectrons via tertiary photoemission, arXiv:2405.06141. † Co-first authors.
In the news: Northeastern Global News, Phys.org, Tech Explorist
Source: Fig. 2, G. Dhakal et al., Physical Review Research 3, 023170 (2021).
Copyright / license: © 2021 The Authors. Published by the American Physical Society under CC BY 4.0.
Cleavage-Dependent Surface Electronic Structure
Cleavage-Dependent Surface Electronic Structure
Gyanendra Dhakal, M. Mofazzel Hosen, Wei-Chi Chiu, et al.
Cleaving Plane-Dependent Electronic Structures of Transition Metal Diarsenides, Physical Review Research 3, 023170 (2021).
Combining angle-resolved photoemission spectroscopy with first-principles calculations, we resolved how different cleavage planes expose distinct surface electronic structures in transition-metal diarsenides. The comparison separates apparently Dirac-like dispersions from topologically trivial surface bands and demonstrates why surface termination must be included when interpreting ARPES measurements.
Source: Fig. 4, A. Pulkkinen et al., Physical Review B 111, 235145 (2025).
Copyright: © 2025 American Physical Society.
Momentum-Space Signatures of a Topological Transition
Momentum-Space Signatures of a Topological Transition
Aki Pulkkinen, Veenavee Nipunika Kothalawala, Kosuke Suzuki, Bernardo Barbiellini, Johannes Nokelainen, Wei-Chi Chiu, et al.
Probing the Semiconductor–Dirac-Semimetal Transition in Na–Sb–Bi Alloys with X-ray Compton Scattering, Physical Review B 111, 235145 (2025).
X-ray Compton scattering provides a momentum-space probe of the semiconductor–Dirac-semimetal transition in Na–Sb–Bi alloys. Comparing measured Compton-profile differences with first-principles and atomic models connects charge redistribution and spin–orbit coupling to the electronic-structure transition. This work also belongs to the Topological Materials for Energy Storage research theme.
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