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Controlling the magnetotransport properties of magnetic topological insulator Crx(BiySb1−y)2−xTe3 thin films via molecular beam epitaxy

Jan Karthein1,2,*, Jonas Buchhorn1,2, Kaycee Underwood1,2,†, Abdur Rehman Jalil1,3, Max Vaßen-Carl1,2, Peter Schüffelgen1,2, Detlev Grützmacher1,2, and Thomas Schäpers1,2,‡

  • *Contact author: j.karthein@fz-juelich.de.de
  • †Present address: Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain.
  • ‡Contact author: th.schaepers@fz-juelich.de
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Phys. Rev. Materials 9, 124202 – Published 10 December, 2025

DOI: https://doi.org/10.1103/8m2h-83zm

Abstract

In this work we present a systematic in-depth study of how we can alter the magnetotransport properties of magnetic topological insulator thin films by tuning the parameters of the molecular-beam epitaxy. First, we show how a varying substrate temperature changes the surface morphology and, when chosen properly, leads to a high crystal quality. Next, the effect of the chromium concentration on the film roughness and crystal quality is investigated. Finally, both the substrate temperature and the chromium concentration are investigated with respect to their effect on the magnetotransport properties of the magnetic topological insulator thin films. It becomes apparent that the substrate temperature and the chromium concentration can be used to tune the Fermi level of the film which allows to make the material intrinsically charge neutral. A very low chromium concentration furthermore allows to tune the magnetic topological insulator into a regime where strong superconducting correlations can be expected when combining the material with a superconductor.

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Phys. Rev. Materials 9, 124202– Published 10 December, 2025
  • Received 17 July 2025
  • Revised 23 September 2025
  • Accepted 17 November 2025
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