Surface Electronic Structure Engineering of Manganese Bismuth Tellurides Guided by Micro‐Focused Angle‐Resolved Photoemission

• Published in: Advanced materials (Weinheim) 2023-09, Vol.35 (36), p.e2301907-n/a
• Main Authors: Volckaert, Klara, Majchrzak, Paulina, Biswas, Deepnarayan, Jones, Alfred J. H., Bianchi, Marco, Jiang, Zhihao, Dubourg, Raphaël, Stenshøj, Rasmus Ørnekoll, Jensen, Mads Lykke, Jones, Nykola C., Hoffmann, Søren V., Mi, Jian‐Li, Bremholm, Martin, Pan, Xing‐Chen, Chen, Yong P., Hofmann, Philip, Miwa, Jill A., Ulstrup, Søren
• Format: Article
• Language: English
• Subjects: alkali doping; Banded structure; Bismuth tellurides; Deposition; Doping; Electron transport; Electronic structure; Magnetic properties; magnetic topological insulators; Manganese; microARPES; Photoelectric emission; Quantum wells; Rubidium; surface band structure engineering; Topological insulators; tunable topological bands
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202301907

Modification of the electronic structure of quantum matter by ad atom deposition allows for directed fundamental design of electronic and magnetic properties. This concept is utilized in the present study in order to tune the surface electronic structure of magnetic topological insulators based on MnBi2Te4. The topological bands of these systems are typically strongly electron‐doped and hybridized with a manifold of surface states that place the salient topological states out of reach of electron transport and practical applications. In this study, micro‐focused angle‐resolved photoemission spectroscopy (microARPES) provides direct access to the termination‐dependent dispersion of MnBi2Te4 and MnBi4Te7 during in situ deposition of rubidium atoms. The resulting band structure changes are found to be highly complex, encompassing coverage‐dependent ambipolar doping effects, removal of surface state hybridization, and the collapse of a surface state band gap. In addition, doping‐dependent band bending is found to give rise to tunable quantum well states. This wide range of observed electronic structure modifications can provide new ways to exploit the topological states and the rich surface electronic structures of manganese bismuth tellurides. Dramatic modifications of the surface electronic structures of the magnetic topological insulator compounds MnBi2Te4 and MnBi4Te7 are directly visualized using micro‐focused angle‐resolved photoemission spectroscopy. A general method to achieve a minimal dispersion with topological bands close to the Fermi energy is demonstrated across the compounds.