Surface-Driven Evolution of the Anomalous Hall Effect in Magnetic Topological Insulator MnBi₂Te₄ Thin Films

Journal Article · 26 May 2022 · Advanced Functional Materials

DOI: https://doi.org/10.1002/adfm.202202234 · OSTI ID:1883671

Mazza, Alessandro R. ^[1]; Lapano, Jason ^[1]; Meyer III, Harry M. ^[1]; Nelson, Christopher T. ^[1]; Smith, Tyler ^[1]; Pai, Yun‐Yi ^[1]; Noordhoek, Kyle ^[1]; Lawrie, Benjamin J. ^[1]; Charlton, Timothy R. ^[1]; Moore, Robert G. ^[1]; Ward, T. Zac ^[1]; Du, Mao‐Hua ^[1]; Eres, Gyula ^[1]; Brahlek, Matthew  ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

We report understanding the effects of the interfacial modification to the functional properties of magnetic topological insulator thin films is crucial for developing novel technological applications from spintronics to quantum computing. Here, a large electronic and magnetic response is reported to be induced in the intrinsic magnetic topological insulator MnBi₂Te₄ by controlling the propagation of surface oxidation. It is shown that the formation of the surface oxide layer is confined to the top 1–2 unit cells but drives large changes in the overall magnetic response. Specifically, a dramatic reversal of the sign of the anomalous Hall effect is observed to be driven by finite thickness magnetism, which indicates that the film splits into distinct magnetic layers each with a unique electronic signature. These data reveal a delicate dependence of the overall magnetic and electronic response of MnBi₂Te₄ on the stoichiometry of the top layers. This study suggests that perturbations resulting from surface oxidation may play a non-trivial role in the stabilization of the quantum anomalous Hall effect in this system and that understanding targeted modifications to the surface may open new routes for engineering novel topological and magnetic responses in this fascinating material.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); National Quantum Information Science (QIS) Research Centers (United States). The Quantum Science Center (QSC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1883671
• Journal Information: Advanced Functional Materials, Journal Name: Advanced Functional Materials Journal Issue: 28 Vol. 32; ISSN 1616-301X
• Publisher: WileyCopyright Statement
• Country of Publication: United States
• Language: English