Nanoscale detection and control of the magnetic order underpins a spectrum of condensed-matter research and device functionalities involving magnetism. The key principle involved is the breaking of time-reversal symmetry, which in ferromagnets is generated by an internal magnetization. However, the presence of a net magnetization limits device scalability and compatibility with phases, such as superconductors and topological insulators. Recently, altermagnetism has been proposed as a solution to these restrictions, as it shares the enabling time-reversal-symmetry-breaking characteristic of ferromagnetism, combined with the antiferromagnetic-like vanishing net magnetization1-4. So far, altermagnetic ordering has been inferred from spatially averaged probes4-19. Here we demonstrate nanoscale imaging of altermagnetic states from 100-nanometre-scale vortices and domain walls to 10-micrometre-scale single-domain states in manganese telluride (MnTe)2,7,9,14-16,18,20,21. We combine the time-reversal-symmetry-breaking sensitivity of X-ray magnetic circular dichroism12 with magnetic linear dichroism and photoemission electron microscopy to achieve maps of the local altermagnetic ordering vector. A variety of spin configurations are imposed using microstructure patterning and thermal cycling in magnetic fields. The demonstrated detection and controlled formation of altermagnetic spin configurations paves the way for future experimental studies across the theoretically predicted research landscape of altermagnetism, including unconventional spin-polarization phenomena, the interplay of altermagnetism with superconducting and topological phases, and highly scalable digital and neuromorphic spintronic devices3,14,22-24.

Diamond Light Source Harwell Science and Innovation Campus Didcot UK

Institut de Physique École Polytechnique Fédérale de Lausanne Lausanne Switzerland

Institute of Physics Czech Academy of Sciences Prague Czech Republic

Institute of Physics Johannes Gutenberg University Mainz Germany

MAX 4 Laboratory Lund Sweden

Max Planck Institute for Chemical Physics of Solids Dresden Germany

Max Planck Institute for the Physics of Complex Systems Dresden Germany

Nanoscale and Microscale Research Centre University of Nottingham Nottingham UK

Photon Science Division Paul Scherrer Institut Villigen Switzerland

School of Physics and Astronomy University of Nottingham Nottingham UK

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Šmejkal, L., González-Hernández, R., Jungwirth, T. & Sinova, J. Crystal time-reversal symmetry breaking and spontaneous Hall effect in collinear antiferromagnets. Sci. Adv.6, eaaz8809 (2020). PubMed PMC

Šmejkal, L., Sinova, J. & Jungwirth, T. Beyond conventional ferromagnetism and antiferromagnetism: a phase with nonrelativistic spin and crystal rotation symmetry. Phys. Rev. X12, 031042 (2022).

Šmejkal, L., Sinova, J. & Jungwirth, T. Emerging research landscape of altermagnetism. Phys. Rev. X12, 040501 (2022).

Šmejkal, L., MacDonald, A. H., Sinova, J., Nakatsuji, S. & Jungwirth, T. Anomalous Hall antiferromagnets. Nat. Rev. Mater.7, 482–496 (2022).

Feng, Z. et al. An anomalous Hall effect in altermagnetic ruthenium dioxide. Nat. Electron.5, 735–743 (2022).

Reichlova, H. et al. Observation of a spontaneous anomalous Hall response in the Mn5Si3 d-wave altermagnet candidate. Nat. Commun.15, 4961 (2024). PubMed PMC

Gonzalez Betancourt, R. et al. Spontaneous anomalous Hall effect arising from an unconventional compensated magnetic phase in a semiconductor. Phys. Rev. Lett.130, 036702 (2023). PubMed

Tschirner, T. et al. Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2. APL Mater.11, 101103 (2023).

Kluczyk, K. et al. Coexistence of anomalous Hall effect and weak magnetization in a nominally collinear antiferromagnet MnTe. Phys. Rev. B110, 155201 (2024).

Wang, M. et al. Emergent zero-field anomalous Hall effect in a reconstructed rutile antiferromagnetic metal. Nat. Commun.14, 8240 (2023). PubMed PMC

Han, L. et al. Electrical 180° switching of Néel vector in spin-splitting antiferromagnet. Sci. Adv.10, eadn0479 (2024). PubMed PMC

Hariki, A. et al. X-ray magnetic circular dichroism in altermagnetic α-MnTe. Phys. Rev. Lett.132, 176701 (2024). PubMed

Fedchenko, O. et al. Observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO2. Sci. Adv.10, eadj4883 (2024). PubMed PMC

Krempaskỳ, J. et al. Altermagnetic lifting of Kramers spin degeneracy. Nature626, 517–522 (2024). PubMed PMC

Lee, S. et al. Broken Kramers degeneracy in altermagnetic MnTe. Phys. Rev. Lett.132, 036702 (2024). PubMed

Osumi, T. et al. Observation of a giant band splitting in altermagnetic MnTe. Phys. Rev. B109, 115102 (2024).

Reimers, S. et al. Direct observation of altermagnetic band splitting in CrSb thin films. Nat. Commun.15, 2116 (2024). PubMed PMC

Hajlaoui, M. et al. Temperature dependence of relativistic valence band splitting induced by an altermagnetic phase transition. Preprint at https://arxiv.org/abs/2401.09187 (2024). PubMed

Lin, Z. et al. Observation of giant spin splitting and d-wave spin texture in room temperature altermagnet RuO2. Preprint at https://arxiv.org/abs/2402.04995 (2024).

Lovesey, S., Khalyavin, D. & Van Der Laan, G. Templates for magnetic symmetry and altermagnetism in hexagonal MnTe. Phys. Rev. B108, 174437 (2023).

Mazin, I. Altermagnetism in MnTe: origin, predicted manifestations, and routes to detwinning. Phys. Rev. B107, L100418 (2023).

Leeb, V., Mook, A., Šmejkal, L. & Knolle, J. Spontaneous formation of altermagnetism from orbital ordering. Phys. Rev. Lett.132, 236701 (2024). PubMed

Beenakker, C. & Vakhtel, T. Phase-shifted Andreev levels in an altermagnet Josephson junction. Phys. Rev. B108, 075425 (2023).

Fernandes, R. M., De Carvalho, V. S., Birol, T. & Pereira, R. G. Topological transition from nodal to nodeless Zeeman splitting in altermagnets. Phys. Rev. B109, 024404 (2024).

Nolting, F. et al. Direct observation of the alignment of ferromagnetic spins by antiferromagnetic spins. Nature405, 767–769 (2000). PubMed

Wadley, P. et al. Current polarity-dependent manipulation of antiferromagnetic domains. Nat. Nanotechnol.13, 362–365 (2018). PubMed

Chmiel, F. P. et al. Observation of magnetic vortex pairs at room temperature in a planar α-Fe2O3/Co heterostructure. Nat. Mater.17, 581–585 (2018). PubMed

Krizek, F. et al. Atomically sharp domain walls in an antiferromagnet. Sci. Adv.8, eabn3535 (2022). PubMed PMC

Jani, H. et al. Antiferromagnetic half-skyrmions and bimerons at room temperature. Nature590, 74–79 (2021). PubMed

Amin, O. et al. Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature. Nat. Nanotechnol.18, 849–853 (2023). PubMed PMC

Gomonay, E. & Loktev, V. Spintronics of antiferromagnetic systems. Low Temp. Phys.40, 17–35 (2014).

Folven, E. et al. Effects of nanostructuring and substrate symmetry on antiferromagnetic domain structure in LaFeO3 thin films. Phys. Rev. B84, 220410 (2011).

Reimers, S. et al. Defect-driven antiferromagnetic domain walls in CuMnAs films. Nat. Commun.13, 724 (2022). PubMed PMC

Reimers, S. et al. Magnetic domain engineering in antiferromagnetic CuMnAs and Mn2Au. Phys. Rev. Appl.21, 064030 (2024).

Witte, K. et al. From 2D STXM to 3D imaging: soft X-ray laminography of thin specimens. Nano Lett.20, 1305–1314 (2020). PubMed