Termination-Dependent Surface Fermiology in the Intercalated Altermagnet CoNb4Se8
Abstract Altermagnets have recently gained attention for hosting symmetry-enforced spin-split bands despite zero net magnetization. Angle-resolved photoelectron spectroscopy (ARPES) offers direct access to their electronic structure. However, the intrinsic surface sensitivity of this technique complicates the identification of the observed features: Surface states can be misinterpreted as the spin-split counterpart of bulk bands. This issue becomes particularly relevant for layered intercalated systems, where micrometer-sized domains with distinct terminations often coexist on a cleaved surface. We discuss this scenario for CoNb4Se8, one of the first established layered altermagnets. Supported by density functional theory calculations, we employ micro-ARPES to probe individual domains and reveal two contrasting surface terminations. We identify Co- and Se-terminated domains with characteristic surface states arising from bulk-surface connectivity of the material. Our work shows that termination-dependent surface contributions are essential for the reliable spectroscopic identification of altermagnetism and for assessing its presence across the family of layered materials.
Authors
- Matteo Calandra (ORCID: https://orcid.org/0000-0003-1505-2535)
- Matthieu Jamet (ORCID: https://orcid.org/0000-0002-8247-4677)
- Andrea Locatelli (ORCID: https://orcid.org/0000-0002-8072-7343)
- Sammar Tayyab (ORCID: https://orcid.org/0009-0000-1736-9187)
- Paolo Moras (ORCID: https://orcid.org/0000-0002-7771-8737)
- Tevfik Onur Menteş (ORCID: https://orcid.org/0000-0003-0413-9272)
- Chiara Bigi (ORCID: https://orcid.org/0000-0003-0977-3993)
- Davide Romanin (ORCID: https://orcid.org/0000-0003-1094-5369)
- Alessandro De Vita (ORCID: https://orcid.org/0000-0001-9413-2810)
- Ilija Zeljkovic (ORCID: https://orcid.org/0000-0001-9966-2140)
- Matthew D. Watson (ORCID: https://orcid.org/0000-0002-0737-2814)
- Federico Mazzola (ORCID: https://orcid.org/0000-0002-5380-4374)
- Polina Makarovna Sheverdyaeva (ORCID: https://orcid.org/0000-0002-4231-1638)
- Vincent Polewczyk (ORCID: https://orcid.org/0000-0003-0932-6376)
- Federico Motti (ORCID: https://orcid.org/0000-0003-2684-0764)
- Pietro Maria Forcella (ORCID: https://orcid.org/0000-0003-2846-2875)
- Matteo Jugovac (ORCID: https://orcid.org/0000-0001-9525-3980)
- Jill A. Miwa (ORCID: https://orcid.org/0000-0001-8392-2630)
- M. Szpytma (ORCID: https://orcid.org/0000-0002-2615-0854)
- Christopher Candelora (ORCID: https://orcid.org/0009-0005-5277-1397)
- Iulia Cojocariu (ORCID: https://orcid.org/0000-0002-6408-3541)
- Younghun Hwang
- My Bang Petersen (ORCID: https://orcid.org/0009-0003-5709-5282)
Institutions
- Boston College (US)
- Ulsan College (KR)
- Centre National de la Recherche Scientifique (FR)
- University of Padua (IT)
- University of Trieste (IT)
- University of Trento (IT)
- Université de Versailles Saint-Quentin-en-Yvelines (FR)
- Aarhus University (DK)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- Université Paris-Saclay (FR)
- Fritz Haber Institute of the Max Planck Society (DE)
- Synchrotron soleil (FR)
- Elettra-Sincrotrone Trieste S.C.p.A. (IT)
- Diamond Light Source (GB)
- CEA Grenoble (FR)
- Centre de Nanosciences et de Nanotechnologies (FR)
- Institute for Basic Science (KR)
- Istituto Nazionale di Fisica Nucleare, Sezione di Padova (IT)
- Institute of Structure of Matter (IT)
- Spintronique et Technologie des Composants (FR)
- Technische Universität Berlin (DE)
- AGH University of Krakow (PL)
- Sapienza University of Rome (IT)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Nano Letters
- Published
- 2026-10-19
- DOI
- https://doi.org/10.1021/acs.nanolett.6c01819
- Primary Topic
- Magnetic properties of thin films
- Type
- article
- Field-Weighted Citation Impact
- 0.00