This book presents high-resolution angle-resolved photoemission spectroscopy (ARPES) experiments on kagome superconductors KV3Sb5, RbV3Sb5, and CsV3Sb5—an ideal material family for studying rich physical phenomena originating from the geometric structure of kagome lattice—with the aim of elucidating the electronic structure and the origin of charge density wave (CDW) and superconductivity. The book begins with an introduction to kagome superconductors, followed by a description of ARPES which is the main tool used in the presented work in this book. The part of the experimental results consists of three chapters: The first chapter describes observation of low-energy excitations, Fermi-surface and momentum-dependent CDW gap by high-resolution ARPES on CsV3Sb5 and KV3Sb5; the second chapter shows evolution of electronic states upon alkali-metal dosing and isovalent substitution, and discusses their relation to modulation of physical properties; the other chapter provides the result of micro-ARPES on KV3Sb5, RbV3Sb5, and CsV3Sb5, and demonstrates the surface-termination- and alkali-metal-dependent three dimensional CDW character.
.- Introduction.
.- Photoemission Spectroscopy.
.- Experimental Apparatus.
.- CDW-Induced Band Modification in AV3Sb5.
.- Effects of Cs Dosing and Nb Substitution to CsV3Sb5.
.- Micro-ARPES Study of AV3Sb5.
.- Summary.
Takemi Kato is a postdoctoral researcher at the Advanced Institute for Materials Research, Tohoku University. He received his Bachelor, Master and Doctor of Science from Tohoku University in 2019, 2021 and 2024, respectively. He joined the group led by Professor Takafumi Sato in 2018, and started his work using angle-resolved photoemission spectroscopy which is an experimental technique to directly observe electronic states of materials. During his doctor program, he mainly studied electronic structure of newly discovered kagome superconductors, especially focusing on the electronic nature of charge-density wave.
