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説明:

A gapped Dirac cone in antiferromagnetic topological insulators (AFM-TIs) is essential for realizing exotic quantum phenomena, such as the quantum anomalous Hall effect and axion electrodynamics. In the prototypical AFM-TI MnBi2Te4, however, the observed energy gap in the Dirac cone is significantly smaller
than theoretical predictions or nearly absent. This long-standing discrepancy not only limits the feasibility of high-temperature applications but also hinders a full understanding of the interplay between bulk magnetism and topological surface state, a central issue in topological physics. Here we demonstrate that NdBi, a recently identified AFM-TI, hosts a surface Dirac cone with a sizable gap of 15 meV, in excellent agreement with density functional theory predictions (12 meV). This provides the first unambiguous spectroscopic evidence of an intrinsic magnetic topological insulator in NdBi. This was made possible by high-resolution, laser-based spin- and angle-resolved photoemission spectroscopy, which clearly separates the spin-polarized surface Dirac cone from adjacent bulk states for the first time. We further show that the gap originates from cooperative exchange interactions mediated by both bulk and surface magnetism, driven by strong coupling between localized Nd 4f moments and itinerant carriers. These findings identify NdBi as a rare AFM-TI in which the surface Dirac gap reflects intrinsic magnetism rather than surface-related artifacts. The temperature-tunable nature of this Dirac gap governed by magnetism opens avenues for the realization of high-temperature topological spintronic functionalities.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Antiferromagnetic topological insulators, Angle-resolved photoemission spectroscopy

刊行年月日: 2026-09-15

出版者: Springer Science and Business Media LLC

掲載誌:

• Nature Communications (ISSN: 20411723) vol. 17 issue. 1

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原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41467-026-77571-4

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更新時刻: 2026-10-19 08:49:18 +0900

MDRでの公開時刻: 2026-10-19 10:30:08 +0900