{ "abstract": "Altermagnetism defies conventional classifications of collinear magnetic phases, combining compensated magnetization with momentum‐dependent, nonrelativistic spin splitting. While altermagnetic band splitting has been established in three‐dimensional compounds such as MnTe and CrSb, layered altermagnets remain far less explored spectroscopically. Here, combining termination‐resolved micro‐ARPES, fine photon‐energy mapping, spin‐ARPES, and density functional theory, we map the three‐dimensional fermiology of the layered g ‐wave altermagnet , obtained by ordered Co intercalation of 2H‐. We resolve the spin–split branches of the altermagnetic pairs directly in the raw photoemission spectra and, with spin‐ARPES at these experimentally identified momenta, show the reversal of the spin polarization at opposite momenta and between two regions of the sample, consistent with opposite time‐reversal domains, and its absence along the symmetry‐protected nodal –K direction. We further report a weak low‐temperature anomaly near T 0 ≈ 50–60 K, detected by magnetometry, temperature‐dependent micro‐ARPES, and ultrafast reflectivity, whose microscopic origin remains open. These results provide a momentum‐resolved benchmark of the electronic structure of a layered altermagnet.", "abstract_shown": true, "affiliations": [ "Fritz Haber Institut der Max Planck Gesellschaft Berlin Germany", "Institut für Physik und Astronomie Technische Universität Berlin Berlin Germany", "FHI - Fritz-Haber-Institut der Max-Planck-Gesellschaft (Faradayweg 4-6- D-14195 Berlin - Germany)", "Synchrotron SOLEIL Saint‐Aubin France", "SSOLEIL - Synchrotron SOLEIL (L'Orme des Merisiers Saint-Aubin - BP 48 91192 GIF-sur-YVETTE CEDEX - France)", "Centre de Nanosciences et de Nanotechnologies Université Paris‐Saclay, CNRS Paris France", "C2N - Centre de Nanosciences et de Nanotechnologies (10 Boulevard Thomas Gobert, 91120, Palaiseau - France)", "Université Paris-Saclay (Bâtiment Bréguet, 3 Rue Joliot Curie 2e ét, 91190 Gif-sur-Yvette - France)", "Diamond Light Source Ltd Harwell Science and Innovation Campus Didcot UK", "DIAMOND Light source (Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE - United Kingdom)", "Université Paris‐Saclay Versailles France", "GEMAC - Groupe d'Etude de la Matière Condensée (URF de Sciences Bâtiment Fermat 45 avenue des Etats Unis 78035 Versailles - France)", "Department of Physics and Astronomy, Interdisciplinary Nanoscience Center Aarhus University Aarhus C Denmark", "IOM - CNR Istituto Officina dei Materiali (Laboratorio TASC Area Science Park - Basovizza Ed.MM, Strada Statale 14 Km 163,5 I-34149 Trieste - Italy)", "CNR‐Istituto Officina dei Materiali (IOM) Unità di Trieste Basovizza (TS) Italy", "Dipartimento di Fisica Università degli Studi di Trieste Trieste Italy", "Elettra ‐ Sincrotrone Trieste S.C.p.A. Trieste Italy", "CNR-SPIN and Department of Physics “E. Pancini (Piazzale V. Tecchio 80, I-80125 Naples - Italy)", "CNR‐SPIN Universitá di Salerno Fisciano (SA) Italy", "NBI - Niels Bohr Institute [Copenhagen] (Blegdamsvej 17, DK-2100 Copenhagen - Denmark)", "Niels Bohr Institute University of Copenhagen Copenhagen Denmark", "Monash University [Clayton] (Clayton, VIC 3800, Australia - Australia)", "School of Physics and Astronomy Monash University Victoria Australia", "Department of Physics Boston College Chestnut Hill Massachusetts USA", "ETH Zürich Zürich Switzerland", "Institute for Theoretical Physics and Astrophysics University of Würzburg Würzburg Germany", "CNR‐SPIN Complesso di Monte S. Angelo Napoli Italy", "Physics Department University of Napoli “Federico II” Napoli Italy", "Nanoscience Center, Niels Bohr Institute University of Copenhagen Copenhagen Denmark", "European Spallation Source ERIC ‐ Data Management and Software Center Kgs. Lyngby Denmark", "Faculty of Physics and Applied Computer Science AGH University of Krakow Krakow Poland", "Center for Artificial Low‐Dimensional Electronic Systems Institute for Basic Science Namgu Pohang Republic of Korea", "Department of Physics Pohang University of Science and Technology Pohang‐si Gyeongsangbuk‐do Republic of Korea", "Univ. Grenoble Alpes, CEA, CNRS, IRIG‐SPINTEC Grenoble France", "Electricity and Electronics and Semiconductor Applications Ulsan College Ulsan Republic of Korea", "Department of Physics University of Trento Povo Italy", "CNR‐Istituto di Struttura della Materia (CNR‐ISM) Trieste Italy", "Department of Physics and Astronomy ‘Galileo Galilei' University of Padova Padova Italy" ], "article_type": null, "arxiv": null, "author_total": 48, "authors": [ { "affs": [ 0, 1, 2 ], "name": "Alessandro De Vita" }, { "affs": [ 3, 4 ], "name": "Chiara Bigi", "orcid": "0000-0003-0977-3993" }, { "affs": [ 5, 6, 7 ], "name": "Davide Romanin", "orcid": "0000-0003-1094-5369" }, { "affs": [ 8, 9 ], "name": "Matthew D. Watson", "orcid": "0000-0002-0737-2814" }, { "affs": [ 10, 11 ], "name": "Vincent Polewczyk", "orcid": "0000-0003-0932-6376" }, { "affs": [ 3 ], "name": "Marta Zonno", "orcid": "0000-0003-0668-5146" }, { "affs": [ 3, 4 ], "name": "F. Bertran", "orcid": "0000-0002-2416-0514" }, { "affs": [ 5 ], "name": "Pietro Maria Forcella", "orcid": "0000-0003-2846-2875" }, { "affs": [ 12, 13 ], "name": "My Bang Petersen", "orcid": "0009-0003-5709-5282" }, { "affs": [ 14, 13 ], "name": "Federico Motti", "orcid": "0000-0003-2684-0764" }, { "affs": [ 14 ], "name": "Giovanni Vinai", "orcid": "0000-0003-4882-663X" }, { "affs": [ 15 ], "name": "Manuel Tuniz", "orcid": "0000-0003-2459-2031" }, { "affs": [ 16, 17 ], "name": "Federico Cilento", "orcid": "0000-0002-4121-1694" }, { "affs": [ 18, 19 ], "name": "Mario Cuoco", "orcid": "0000-0002-7325-8331" }, { "affs": [ 20, 19 ], "name": "Brian M. Andersen", "orcid": "0000-0002-9786-7553" }, { "affs": [ 20 ], "name": "Andreas Kreisel", "orcid": "0000-0003-3028-377X" }, { "affs": [ 18, 21 ], "name": "Luciano Jacopo D’Onofrio", "orcid": "0000-0002-6358-992X" }, { "affs": [ 22 ], "name": "Oliver J. Clark", "orcid": "0000-0002-3092-9465" }, { "affs": [ 22 ], "name": "Mark T. Edmonds", "orcid": "0000-0001-8054-5470" }, { "affs": [ 23 ], "name": "Christopher Candelora", "orcid": "0009-0005-5277-1397" }, { "affs": [ 23 ], "name": "Muxian Xu", "orcid": "0009-0002-5412-1206" }, { "affs": [ 23 ], "name": "Siyu Cheng", "orcid": "0009-0000-7825-9379" }, { "affs": [ 23 ], "name": "Alexander LaFleur" }, { "affs": [ 24 ], "name": "Tommaso Antonelli", "orcid": "0000-0002-4990-7813" }, { "affs": [ 25 ], "name": "Giorgio Sangiovanni", "orcid": "0000-0003-2218-2901" }, { "affs": [ 25 ], "name": "Lorenzo Del Re", "orcid": "0000-0002-8765-2866" }, { "affs": [ 14 ], "name": "I. Vobornik", "orcid": "0000-0001-9957-3535" }, { "affs": [ 14 ], "name": "Jun Fujii", "orcid": "0000-0003-3208-802X" }, { "affs": [ 26 ], "name": "F. Miletto Granozio", "orcid": "0000-0002-9417-7848" }, { "affs": [ 26 ], "name": "A. Sambri", "orcid": "0000-0003-1228-4226" }, { "affs": [ 27 ], "name": "Emiliano Di Gennaro", "orcid": "0000-0003-4231-9776" }, { "affs": [ 28 ], "name": "H. Jacobsen", "orcid": "0000-0001-6950-3990" }, { "affs": [ 29 ], "name": "H. Jacobsen", "orcid": "0000-0001-6950-3990" }, { "affs": [ 15, 16 ], "name": "Iulia Cojocariu", "orcid": "0000-0002-6408-3541" }, { "affs": [ 16, 30 ], "name": "Marcin Szpytma" }, { "affs": [ 16 ], "name": "Andrea Locatelli", "orcid": "0000-0002-8072-7343" }, { "affs": [ 16 ], "name": "Tevfik Onur Menteş", "orcid": "0000-0003-0413-9272" }, { "affs": [ 31, 32 ], "name": "Won Seop Song", "orcid": "0009-0005-9979-9127" }, { "affs": [ 31, 32 ], "name": "Jun Sung Kim", "orcid": "0000-0002-1413-7265" }, { "affs": [ 33 ], "name": "Matthieu Jamet", "orcid": "0000-0002-8247-4677" }, { "affs": [ 33 ], "name": "Jean‐François Jacquot" }, { "affs": [ 14 ], "name": "P. Orgiani", "orcid": "0000-0002-1082-9651" }, { "affs": [ 0, 1 ], "name": "Ralph Ernstorfer", "orcid": "0000-0001-6665-3520" }, { "affs": [ 23 ], "name": "Ilija Zeljkovic", "orcid": "0000-0001-9966-2140" }, { "affs": [ 34 ], "name": "Y. T. Hwang", "orcid": "0009-0008-7628-3373" }, { "affs": [ 35 ], "name": "Jill A. Miwa", "orcid": "0000-0001-8392-2630" }, { "affs": [ 12 ], "name": "Jill A. Miwa", "orcid": "0000-0001-8392-2630" }, { "affs": [ 36, 26, 37 ], "name": "Federico Mazzola", "orcid": "0000-0002-5380-4374" } ], "bibtex": "https://research.draconitic.com/paper/e0dmm69cnmr5r.bib", "cited_by": 21, "doi": "10.1002/adma.75367", "fulltext_url": null, "id": "e0dmm69cnmr5r", "issns": [ "0935-9648", "1521-4095" ], "landing_url": "https://doi.org/10.1002/adma.75367", "language": "en", "licence": "CC-BY", "licence_label": "CC BY", "licence_source": "journal", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "3104|Magnetic properties of thin films" ] ], "openalex": "W4415957658", "pdf_url": null, "pmcid": null, "pmid": "42894274", "published": "2026-10-18", "publisher": null, "ris": "https://research.draconitic.com/paper/e0dmm69cnmr5r.ris", "sources": [ { "first_seen": "2026-11-07T13:20:45Z", "native_id": "W4415957658", "source": "openalex", "url": "https://doi.org/10.1002/adma.75367" } ], "subjects": [ { "field": "physics", "origin": "openalex:3104|Magnetic properties of thin films", "subfield": "condensed-matter" } ], "title": "Robust Spin Splitting and Fermiology in the Layered Altermagnet CoNb4Se8", "title_text": "Robust Spin Splitting and Fermiology in the Layered Altermagnet CoNb4Se8", "type": "peer-reviewed", "updated_at": "2026-11-10T13:21:00Z", "url": "https://research.draconitic.com/paper/e0dmm69cnmr5r", "venue": "Advanced Materials", "versions": [] }