Evolution of Band Structure in a Kagome Superconductor Cs(V1-xCrx)3Sb5: Toward Universal Understanding of CDW and Superconducting Phase Diagrams

• Published in: arXiv.org 2024-07
• Main Authors: Suzuki, Shuto, Kato, Takemi, Li, Yongkai, Nakayama, Kosuke, Wang, Zhiwei, Souma, Seigo, Ozawa, Kenichi, Kitamura, Miho, Horiba, Koji, Kumigashira, Hiroshi, Takahashi, Takashi, Yao, Yugui, Sato, Takafumi
• Format: Article
• Language: English
• Subjects: Cesium; Charge density waves; Chromium; Doping; Electron states; Materials substitution; Phase diagrams; Photoelectric emission; Saddle points; Superconductivity; Superconductors
• ISSN: 2331-8422

Kagome superconductors AV3Sb5 (A = K, Rb, Cs) exhibit a characteristic superconducting and charge-density wave (CDW) phase diagram upon carrier doping and chemical substitution. However, the key electronic states responsible for such a phase diagram have yet to be clarified. Here we report a systematic micro-focused angle-resolved photoemission spectroscopy (ARPES) study of Cs(V1-xCrx)3Sb5 as a function of Cr content x, where Cr substitution causes monotonic reduction of superconducting and CDW transition temperatures. We found that the V-derived bands forming saddle points at the M point and Dirac nodes along high-symmetry cuts show an energy shift due to electron doping by Cr substitution, whereas the Sb-derived electron band at the Gamma point remains almost unchanged, signifying an orbital-selective band shift. We also found that band doubling associated with the emergence of three-dimensional CDW identified at x = 0 vanishes at x = 0.25, in line with the disappearance of CDW. A comparison of band diagrams among Ti-, Nb-, and Cr-substituted Cs(V1-xCrx)3Sb5 suggests the importance to simultaneously take into account the two saddle points at the M point and their proximity to the Fermi energy, to understand the complex phase diagram against carrier doping and chemical pressure.