Berlin 2024 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 37: Poster: Electronic Structure of Surfaces and Spectroscopy of Surface States

O 37.11: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster D

Surface preparation of topological insulator Bi₂Te₃ and ferromagnet La_0.7Sr_0.3MnO₃ for band structure measurements — •Øyvind Finnseth, Damian Brzozowski, Ingrid Hallsteinsen, and Hendrik Bentmann — Norwegian University of Science and Technology

The proximity coupling of topological insulators with magnetically ordered systems in heterostructure systems, wherein the magnetic order serves to break the time reversal symmetry of the topological insulator, have attracted much attention in later years. As components in such a system, we consider thin films of the topological insulator Bi₂Te₃ and ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) grown by pulsed laser deposition. The signature of the topological state of Bi₂Te₃ may be found in the electronic band structure of the surface state. In order to understand the effect of proximity coupling on the surface state in a heterostructure, a full understanding of the properties of its constituents is required. However, the surfaces of both Bi₂Te₃ and LSMO degrade after exposure to air, rendering band structure measurements of surface states challenging. We therefore study surface preparation methods necessary for ARPES measurements on these materials. The studied methods include annealing with and without an oxygen atmosphere for LSMO, along with argon ion sputtering at different energies and duration for both samples. The suitability of each method is evaluated by XPS, yielding information on the presence of contaminants as well as the stoichiometry of the samples, while LEED serves to inspect the crystalline quality of the sample surface.

Keywords: Topological insulators; Magnetic oxides; Surface preparation; ARPES