Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Magnetic ratchet for three-dimensional spintronic memory and logic


One of the key challenges for future electronic memory and logic devices is finding viable ways of moving from today’s two-dimensional structures, which hold data in an xy mesh of cells, to three-dimensional structures in which data are stored in an xyz lattice of cells. This could allow a many-fold increase in performance. A suggested solution is the shift register1,2—a digital building block that passes data from cell to cell along a chain. In conventional digital microelectronics, two-dimensional shift registers are routinely constructed from a number of connected transistors. However, for three-dimensional devices the added process complexity and space needed for such transistors would largely cancel out the benefits of moving into the third dimension. ‘Physical’ shift registers, in which an intrinsic physical phenomenon is used to move data near-atomic distances, without requiring conventional transistors, are therefore much preferred. Here we demonstrate a way of implementing a spintronic unidirectional vertical shift register between perpendicularly magnetized ferromagnets of subnanometre thickness, similar to the layers used in non-volatile magnetic random-access memory3. By carefully controlling the thickness of each magnetic layer and the exchange coupling between the layers, we form a ratchet that allows information in the form of a sharp magnetic kink soliton to be unidirectionally pumped (or ‘shifted’) from one magnetic layer to another. This simple and efficient shift-register concept suggests a route to the creation of three-dimensional microchips for memory and logic applications.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Diagrams of solitons and ratchet scheme.
Figure 2: Superlattice stack sequence, major hysteresis loop and soliton propagation.
Figure 3: Soliton propagation with field pulses.


  1. Parkin, S. S. P., Hayashi, M. & Thomas, L. Magnetic domain-wall racetrack memory. Science 320, 190–194 (2008)

    Article  ADS  CAS  Google Scholar 

  2. Allwood, D. A. et al. Magnetic domain-wall logic. Science 309, 1688–1692 (2005)

    Article  ADS  CAS  Google Scholar 

  3. Kawahara, T., Ito, K., Takemura, R. & Ohno, H. Spin-transfer torque RAM technology: review and prospect. Microelectron. Reliab. 52, 613–627 (2012)

    Article  Google Scholar 

  4. Hellwig, O., Berger, A., Kortright, J. B. & Fullerton, E. E. Domain structure and magnetization reversal of antiferromagnetically coupled perpendicular films. J. Magn. Magn. Mater. 319, 13–55 (2007)

    Article  ADS  CAS  Google Scholar 

  5. Wang, R. W., Mills, D. L., Fullerton, E. E., Mattson, J. E. & Bader, S. D. Surface spin-flop transition in Fe/Cr(211) superlattices — experiment and theory. Phys. Rev. Lett. 72, 920–923 (1994)

    Article  ADS  CAS  Google Scholar 

  6. Mühlbauer, S. et al. Skyrmion lattice in a chiral magnet. Science 323, 915–919 (2009)

    Article  ADS  Google Scholar 

  7. Seki, S., Yu, X. Z., Ishiwata, S. & Tokura, Y. Observation of skyrmions in a multiferroic material. Science 336, 198–201 (2012)

    Article  ADS  CAS  Google Scholar 

  8. Baryakhtar, V. G., Chetkin, M. V., Ivanov, B. A. & Gadetskii, S. N. Dynamics of Topological Magnetic Solitons: Experiments and Theory (Springer, 1994)

    Book  Google Scholar 

  9. Lavrijsen, R. et al. Tuning the interlayer exchange coupling between single perpendicularly magnetized CoFeB layers. Appl. Phys. Lett. 100, 052411 (2012)

    Article  ADS  Google Scholar 

  10. Kronmller, H., Parkin, S., eds. Handbook of Magnetism and Advanced Magnetic Materials Vols 1–5 (Wiley, 2007)

  11. Lavrijsen, R. et al. Reduced domain wall pinning in ultrathin Pt/Co100−xBx/Pt with perpendicular magnetic anisotropy. Appl. Phys. Lett. 96, 022501 (2010)

    Article  ADS  Google Scholar 

  12. Lemerle, S. et al. Domain wall creep in an Ising ultrathin magnetic film. Phys. Rev. Lett. 80, 849–852 (1998)

    Article  ADS  CAS  Google Scholar 

  13. Bruno, P. et al. Hysteresis properties of ultrathin ferromagnetic films. J. Appl. Phys. 68, 5759–5766 (1990)

    Article  ADS  CAS  Google Scholar 

  14. Sbiaa, R., Meng, H. & Piramanayagam, S. N. Materials with perpendicular magnetic anisotropy for magnetic random access memory. Phys. Status Solidi RRL 5, 413–419 (2011)

    Article  CAS  Google Scholar 

  15. Gajek, M. et al. Spin torque switching of 20nm magnetic tunnel junctions with perpendicular anisotropy. Appl. Phys. Lett. 100, 132408 (2012)

    Article  ADS  Google Scholar 

  16. Langholz, G., Kandel, A. & Mott, J. L. Foundations of Digital Logic Design (World Scientific, 1998)

    Book  Google Scholar 

  17. Thomson, T., Hu, G. & Terris, B. D. Intrinsic distribution of magnetic anisotropy in thin films probed by patterned nanostructures. Phys. Rev. Lett. 96, 257204 (2006)

    Article  ADS  CAS  Google Scholar 

  18. Baltz, V. et al. Multilevel magnetic nanodot arrays with out of plane anisotropy: the role of intra-dot magnetostatic coupling. Eur. Phys. J. Appl. Phys. 39, 33–38 (2007)

    Article  ADS  CAS  Google Scholar 

  19. Baltz, V. et al. Balancing interlayer dipolar interactions in multilevel patterned media with out-of-plane magnetic anisotropy. Appl. Phys. Lett. 94, 052503 (2009)

    Article  ADS  Google Scholar 

  20. Tudosa, I., Katine, J. A., Mangin, S. & Fullerton, E. E. Perpendicular spin-torque switching with a synthetic antiferromagnetic reference layer. Appl. Phys. Lett. 96, 212504 (2010)

    Article  ADS  Google Scholar 

Download references


R.L. was supported by the Netherlands Organization for Scientific Research and Marie Curie Cofund Action (NWO-Rubicon 680-50-1024). A.F.-P. was supported by a Marie Curie IEF within the Seventh European Community Framework Programme No. 251698; 3DMAG-NANOW. We acknowledge research funding from the European Community under the Seventh Framework Programme Contract No. 247368: 3SPIN.

Author information

Authors and Affiliations



R.L. and R.P.C. planned the experiment; R.L. fabricated the samples; R.L. and J.-H.L. performed the experiments; D.C.M.C.P. performed the dipole field calculations; R.L. analysed the data and wrote the manuscript. All authors discussed the results and contributed to the scientific interpretation as well as to the writing of the manuscript.

Corresponding author

Correspondence to Russell P. Cowburn.

Ethics declarations

Competing interests

R.P.C. and D.C.M.C.P. declare a financial interest: patents related to this research have been filed by the University of Cambridge. The University’s policy is to share financial rewards from the exploitation of patents with the inventors. The remaining authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data, Supplementary Figures 1-6 and additional references. (PDF 1300 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Lavrijsen, R., Lee, JH., Fernández-Pacheco, A. et al. Magnetic ratchet for three-dimensional spintronic memory and logic. Nature 493, 647–650 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing