报告题目：Evidence for electron fractionalization in a kagome metal

报 告 人：Gabriel Aeppli，Head of the Center for Photon Science, Paul Scherrer Institute, Switzerland

报告时间：2024年11月8日15：00

报告地点：物理楼（附中南侧）W101

内容摘要：There are long-standing ideas and experiments concerning the emergence of unconventional quasiparticles in strongly interacting Fermi systems. The most dramatic are the fractional states originally observed for the two-dimensional electron gases in semiconductor heterostructures subjected to perpendicular magnetic fields, and explained shortly thereafter by Laughlin. Others found in zero field are more subtle in the sense that their peculiarity is reflected in their scattering rates which rise linearly together with their energies; these are the "marginal" fermions first conjectured for the layered cuprates also displaying high temperature superconductivity. Here we describe experiments revealing signatures of both types of anomalous quasiparticles in zero applied field. The material is Fe3Sn2, a ferromagnetic “kagome” metal, with numerous Weyl nodes near the Fermi level, and a high Curie temperature of ca. 640K. We investigated the compound using microfocused, laser-based angle-resolved photoemission, together with density functional theory (DFT) and machine learning- based analysis of images. Inelastic X-ray scattering measurements reveal that the correct starting point for understanding this material is not a single kagome layer, but rather a triangular lattice of Fe octahedra.Refs.

Refs.

1.S. A. Ekahana et al., Nature 627, 67-72 (2024)

2.S. A. Ekahana et al., Mach. Learn.: Sci. Technol. 4 035021 https://doi.org/10.1088/2632- 2153/aced7d (2023)

3.M. Yao et al. arXiv:1810.01514

4.W. Zhang et al., Nature Comm. 15, 8905 (2024)

报告人简介：Gabriel Aeppli是苏黎世联邦理工学院（ETH Zürich）和洛桑联邦理工学院（EPF Lausanne）的物理学教授，同时担任保罗谢勒研究所（Paul Scherrer Institute）光子科学中心的负责人。他所有学位均来自麻省理工学院（MIT），包括数学和电气工程的学士学位，以及电气工程的硕士和博士学位。他在IBM、贝尔实验室和NEC工作过，研究领域涵盖从液晶到磁性数据存储的问题。随后，他成为伦敦纳米技术中心的联合创始人兼主任，并担任伦敦大学学院的奎恩教授。此外，他还共同创立了生物纳米咨询公司，目前仍担任该公司的非执行董事。他频繁为全球多个从事科学与技术资金、评估和管理的机构提供顾问服务。他获得的荣誉包括英国物理学会的莫特奖（Mott Prize）、美国物理学会的奥利弗·巴克利奖（Oliver Buckley Prize）、国际纯粹与应用物理联合会的尼尔奖章/国际磁学奖（Néel Medal/International Magnetism Prize），并当选为美国艺术与科学院院士、美国国家科学院院士以及英国皇家学会院士。