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

Abstract

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.

Revealing flat bands and hybridization gaps in a twisted bilayer graphene device with microARPES

“…An optical micrograph of the device is shown in figure 1(a), and a schematic of the architecture and photoemission process is presented in figure 1(b). Photons with tunable energy hν are focused to a spot with minimum lateral diameter of 4.4 µm in the present experiment by using an achromatic capillary mirror [36,38,39]. The kinetic energy and angular distributions of photoemitted electrons are measured using a SPECS Phoibos 150 SAL hemispherical analyzer.…”

“…Here, we present a detailed microARPES study of a tBLG device with a twist angle around the magic angle performed at the SGM4 beamline of the ASTRID2 light source at Aarhus University, Denmark [35,36]. We characterize the spatially-dependent electronic structure of the tBLG device and examine spectral intensity variations stemming from photon energy-dependent photoelectron interference effects.…”