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Direct observation of imprinted antiferromagnetic vortex states in CoO/Fe/Ag(001) discs

Nature Physics volume 7, pages 303–306 (2011)Cite this article

Abstract

In magnetic thin films, a magnetic vortex is a state in which the magnetization vector curls around the centre of a confined structure1. In a thin-film disc, vortex states are characterized by the vortex polarity and the winding number2,3. In ferromagnetic (FM) discs, these two parameters have been shown to govern many fundamental properties of the vortex, such as its gyroscopic rotation4, polarity reversal5,6,7, core motion8 and vortex-pair excitation9. In antiferromagnetic (AFM) discs10, in contrast, there has been only indirect evidence for a vortex state, obtained through the observation of induced FM-ordered spins in the AFM disc11,12,13,14. Here we report the direct observation of an AFM vortex state in the AFM layer of an AFM/FM bilayer system. We have fabricated single-crystalline NiO/Fe/Ag(001) and CoO/Fe/Ag(001) discs, and using X-ray magnetic linear dichroism techniques we observe two types of AFM vortex, one of which has no analogue in FM structures. We also show that a frozen AFM vortex can bias an FM vortex at low temperature.

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Figure 1: XMLD spectra of CoO from CoO/Fe/Ag(001).
Figure 2: Element-specific magnetic-domain images of NiO/Fe and CoO/Fe discs.
Figure 3: Fe magnetic-domain images taken at room temperature on 2-μm-diameter CoO/Fe/Ag(001) discs.
Figure 4: Magnetic-domain images of a 2-μm-diameter CoO(3 nm)/Fe(12 nm)/Ag(001) disc under different conditions.

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References

  1. Shinjo, T., Okuno, T., Hassdorf, R., Shigeto, K. & Ono, T. Magnetic vortex core observation in circular dots of permalloy. Science 289, 930–932 (2000).

    Article  ADS  Google Scholar 

  2. Tretiakov, O. A. & Tchernyshyov, O. Vortices in thin ferromagnetic films and the skyrmion number. Phys. Rev. B 75, 012408 (2007).

    Article  ADS  Google Scholar 

  3. Yu, X. Z. et al. Real-space observation of a two-dimensional skyrmion crystal. Nature 465, 901–904 (2010).

    Article  ADS  Google Scholar 

  4. Choe, S-B. et al. Vortex core-driven magnetization dynamics. Science 304, 420–422 (2004).

    Article  ADS  Google Scholar 

  5. Van Waeyenberge, B. et al. Magnetic vortex core reversal by excitation with short bursts of an alternating field. Nature 444, 461–464 (2006).

    Article  ADS  Google Scholar 

  6. Hertel, R., Gliga, S., Fähnle, M. & Schneider, C. M. Ultrafast nanomagnetic toggle switching of vortex cores. Phys. Rev. Lett. 98, 117201 (2007).

    Article  ADS  Google Scholar 

  7. Yamada, K. et al. Electrical switching of the vortex core in a magnetic disk. Nature Mater. 6, 270–273 (2007).

    Article  ADS  Google Scholar 

  8. Vansteenkiste, A. et al. X-ray imaging of the dynamic magnetic vortex core deformation. Nature Phys. 5, 332–334 (2009).

    Article  ADS  Google Scholar 

  9. Buchanan, K. S. et al. Soliton-pair dynamics in patterned ferromagnetic ellipses. Nature Phys. 1, 172–176 (2005).

    Article  ADS  Google Scholar 

  10. Senthil, T., Vishwanath, A., Balents, L., Sachdev, S. & Fisher, M. P. A. Deconfined quantum critical points. Science 303, 1490–1494 (2004).

    Article  ADS  Google Scholar 

  11. Sort, J. et al. Imprinting vortices into antiferromagnets. Phys. Rev. Lett. 97, 067201 (2006).

    Article  ADS  Google Scholar 

  12. Hoffmann, A., Sort, J., Buchanan, K. S. & Nogués, J. Exchange-biased magnetic vortices. IEEE Trans. Mag. 44, 1968–1973 (2008).

    Article  ADS  Google Scholar 

  13. Salazar-Alvarez, G. et al. Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks. Appl. Phys. Lett. 95, 012510 (2009).

    Article  ADS  Google Scholar 

  14. Tanase, M. et al. Magnetization reversal in circularly exchange-biased ferromagnetic disks. Phys. Rev. B 79, 014436 (2009).

    Article  ADS  Google Scholar 

  15. Wu, J. et al. Direct measurement of rotatable and frozen CoO spins in exchange bias system of CoO/Fe/Ag(001). Phys. Rev. Lett. 104, 217204 (2010).

    Article  ADS  Google Scholar 

  16. Arenholz, E., van der Laan, G., Chopdekar, R. V. & Suzuki, Y. Angle-dependent Ni2+ X-ray magnetic linear dichroism: Interfacial coupling revisited. Phys. Rev. Lett. 98, 197201 (2007).

    Article  ADS  Google Scholar 

  17. van der Laan, G., Arenholz, E., Chopdekar, R. V. & Suzuki, Y. Influence of crystal field on anisotropic X-ray magnetic linear dichroism at the Co2+L2,3 edges. Phys. Rev. B 77, 064407 (2008).

    Article  ADS  Google Scholar 

  18. Nevidomskyy, A. H., Scheiber, C., Sénéchal, D. & Tremblay, A-M. S. Magnetism and d-wave superconductivity on the half-filled square lattice with frustration. Phys. Rev. B 77, 064427 (2008).

    Article  ADS  Google Scholar 

  19. Finazzi, M. et al. Interface coupling transition in a thin epitaxial antiferromagnetic film interacting with a ferromagnetic substrate. Phys. Rev. Lett. 97, 097202 (2006).

    Article  ADS  Google Scholar 

  20. Guslienko, K. et al. Field evolution of magnetic vortex state in ferromagnetic disks. Appl. Phys. Lett. 78, 3848–3850 (2001).

    Article  ADS  Google Scholar 

  21. Uhlig, T. et al. Shifting and pinning of a magnetic vortex core in a permalloy dot by a magnetic field. Phys. Phys. Lett. 95, 237205 (2005).

    Article  ADS  Google Scholar 

  22. Meiklejohn, W. H. & Bean, C. P. New magnetic anisotropy. Phys. Rev. 102, 1413–1414 (1956).

    Article  ADS  Google Scholar 

  23. Nogues, J. & Schuller, I. K. Exchange bias. J. Magn. Magn. Mater. 192, 203–232 (1999).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This work was supported by National Science Foundation Grant DMR-0803305, US Department of Energy Grant DE-AC02-05CH11231, the Korea Foundation for International Cooperation of Science and Technology through the Global Research Laboratory project, the Chinese Education Department and the Western Institute of Nanoelectronics.

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Authors and Affiliations

  1. Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA

    J. Wu, J. S. Park, Y. Meng & Z. Q. Qiu

  2. Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720, USA

    D. Carlton & J. Bokor

  3. Institute of Physics, Chinese Academy of Science, Beijing 100190, China

    Y. Meng & H. W. Zhao

  4. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    E. Arenholz, A. Doran, A. T. Young & A. Scholl

  5. Korea Research Institute of Standards and Science, Yuseong, Daejeon 305-340, Korea

    C. Hwang

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Contributions

J.W. and Z.Q.Q. designed and carried out experiments, analysed data and wrote the paper; D.C. and J.B. patterned the discs and wrote the paper; J.S.P., Y.M., E.A., A.D., A.T.Y., A.S., C.H. and H.W.Z. made the X-ray measurements and discussed results.

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Correspondence to Z. Q. Qiu.

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The authors declare no competing financial interests.

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Wu, J., Carlton, D., Park, J. et al. Direct observation of imprinted antiferromagnetic vortex states in CoO/Fe/Ag(001) discs. Nature Phys 7, 303–306 (2011). https://doi.org/10.1038/nphys1891

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