4.8 Article

Perpendicular full switching of chiral antiferromagnetic order by current

Journal

NATURE
Volume 607, Issue 7919, Pages 474-+

Publisher

NATURE PORTFOLIO
DOI: 10.1038/s41586-022-04864-1

Keywords

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Funding

  1. JST-MIRAI Program [JPMJMI20A1]
  2. JST-CREST [JPMJCR18T3]
  3. JST-PREST [JPMJPR20L7]
  4. MEXT/JSPS-KAKENHI [15H05882, 15H05883, 15K21732, 19H00650, 20K21067, 21H04437, 22H00290]
  5. Spintronics Research Network of Japan (Spin-RNJ)
  6. Hattori Hokokai Foundation
  7. DOE, Office of Science, Basic Energy Sciences [DE-SC0019331]

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This study demonstrates the perpendicular and full spin-orbit torque switching of an antiferromagnetic binary state. The researchers use the chiral antiferromagnet Mn3Sn and fabricate heavy-metal/Mn3Sn heterostructures by molecular beam epitaxy. The experimental results show that the perpendicular octupole polarization in a 30-nanometre-thick Mn3Sn film can achieve 100% switching with a critical current density of less than 15 megaamperes per square centimetre. The study reveals the significance of the perpendicular geometry between the current-induced spin accumulation and the octupole polarization for spin-orbit torque efficiency.
Electrical control of a magnetic state of matter lays the foundation for information technologies and for understanding of spintronic phenomena. Spin-orbit torque provides an efficient mechanism for the electrical manipulation of magnetic orders(1-11). In particular, spin-orbit torque switching of perpendicular magnetization in nanoscale ferromagnetic bits has enabled the development of stable, reliable and low-power memories and computation(12-14). Likewise, for antiferromagnetic spintronics, electrical bidirectional switching of an antiferromagnetic order in a perpendicular geometry may have huge impacts, given its potential advantage for high-density integration and ultrafast operation(15,16). Here we report the experimental realization of perpendicular and full spin-orbit torque switching of an antiferromagnetic binary state. We use the chiral antiferromagnet Mn3Sn (ref. (17)), which exhibits the magnetization-free anomalous Hall effect owing to a ferroic order of a cluster magnetic octupole hosted in its chiral antiferromagnetic state(18). We fabricate heavy-metal/Mn3Sn heterostructures by molecular beam epitaxy and introduce perpendicular magnetic anisotropy of the octupole using an epitaxial in-plane tensile strain. By using the anomalous Hall effect as the readout, we demonstrate 100 per cent switching of the perpendicular octupole polarization in a 30-nanometre-thick Mn3Sn film with a small critical current density of less than 15 megaamperes per square centimetre. Our theory reveals that the perpendicular geometry between the polarization directions of current-induced spin accumulation and of the octupole persistently maximizes the spin-orbit torque efficiency during the deterministic bidirectional switching process. Our work provides a significant basis for antiferromagnetic spintronics.

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