Exfoliated two-dimensional ferromagnets probed by spin polarized scanning tunneling microscopy and photoelectron spectroscopy
Final Report Abstract
Magnetic materials are an essential component of data storage with promising prespectives in data processing. The discovery of stackable, two-dimensional magnetic materials opens up new possibilities for fine-tuning magnetic characteristics and combining different properties. This project investigated the fundamentals of the magnetic materials, with a particular focus on antiferromagnets, that offer the advantage of faster switching speeds. The electronic band structures of various antiferromagnets as weel as structurally similar ferromagnets were mapped using angle-resolved photoemission spectroscopy (ARPES) both above and below the magnetic ordering temperature. This was achieved using the relatively new method of ARPES with spatial resolution on the µm scale. The observed band structure changes of FePS₃, NiPS₃, and MnPS₃ were compared with density functional theory calculations using an effective Hubbard parameter U (DFT+U) to identify the orbital character of the changing bands. The approach provided additional insights into the complex interplay of direct exchange interactions and superexchange in these materials, particularly their connection to the fundamental band structure. Optimizing the sample preparation is crucial for high-quality ARPES data. Initially, we optimized the exfoliation on Au layers deposited on Si/SiO₂, resulting in few monolayers with consistent thickness and lateral dimensions of up to 200 µm. However, these layers exhibited corrugation due to the underlying Au. Moreover, adhesive residues from the tape used during exfoliation are found, which hindered scanning tunneling microscopy measurements. Therefore, in collaboration with the University of Manchester, we established a cantilever-based, polymer-free transfer process. Preliminary measurements on CuCrP₂S₆, a multiferroic van der Waals material prepared on graphite indicate that further optimization is still required.
Publications
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Electronic Band Structure Changes across the Antiferromagnetic Phase Transition of Exfoliated MnPS3 Flakes Probed by μ-ARPES. Nano Letters, 23(22), 10342-10349.
Strasdas, Jeff; Pestka, Benjamin; Rybak, Miłosz; Budniak, Adam K.; Leuth, Niklas; Boban, Honey; Feyer, Vitaliy; Cojocariu, Iulia; Baranowski, Daniel; Avila, José; Dudin, Pavel; Bostwick, Aaron; Jozwiak, Chris; Rotenberg, Eli; Autieri, Carmine; Amouyal, Yaron; Plucinski, Lukasz; Lifshitz, Efrat; Birowska, Magdalena & Morgenstern, Markus
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Identifying Band Structure Changes of FePS3 across the Antiferromagnetic Phase Transition. ACS Nano, 18(47), 32924-32931.
Pestka, Benjamin; Strasdas, Jeff; Bihlmayer, Gustav; Budniak, Adam Krzysztof; Liebmann, Marcus; Leuth, Niklas; Boban, Honey; Feyer, Vitaliy; Cojocariu, Iulia; Baranowski, Daniel; Mearini, Simone; Amouyal, Yaron; Waldecker, Lutz; Beschoten, Bernd; Stampfer, Christoph; Plucinski, Lukasz; Lifshitz, Efrat; Kratzer, Peter & Morgenstern, Markus
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PhD thesis, RWTH Aachen: Understanding Circular Dichroic Angle- Resolved.
H. Boban
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Scattering makes a difference in circular dichroic angle-resolved photoemission. Physical Review B, 111(11).
Boban, Honey; Qahosh, Mohammed; Hou, Xiao; Sobol, Tomasz; Beyer, Edyta; Szczepanik, Magdalena; Baranowski, Daniel; Mearini, Simone; Feyer, Vitaliy; Mokrousov, Yuriy; Zhou, Yishui; Su, Yixi; Jin, Keda; Wichmann, Tobias; Martinez-Castro, Jose; Ternes, Markus; Tautz, F. Stefan; Lüpke, Felix; Schneider, Claus M. ... & Plucinski, Lukasz
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Spin-orbital mixing in the topological ladder of the two-dimensional metal PtTe₂. Physical Review B, 112(15).
Qahosh, M.; Masilamani, M.; Boban, H.; Hou, Xiao; Bihlmayer, G.; Mokrousov, Y.; Karain, W.; Minár, J.; Reinert, F.; Schusser, J.; Schneider, C. M. & Plucinski, L.
