Skip to main content

Thank you for visiting nature.com. 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.

  • Article
  • Published:

Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO

Abstract

Current-induced effective magnetic fields can provide efficient ways of electrically manipulating the magnetization of ultrathin magnetic heterostructures. Two effects, known as the Rashba spin orbit field and the spin Hall spin torque, have been reported to be responsible for the generation of the effective field. However, a quantitative understanding of the effective field, including its direction with respect to the current flow, is lacking. Here we describe vector measurements of the current-induced effective field in Ta|CoFeB|MgO heterostructrures. The effective field exhibits a significant dependence on the Ta and CoFeB layer thicknesses. In particular, a 1 nm thickness variation of the Ta layer can change the magnitude of the effective field by nearly two orders of magnitude. Moreover, its sign changes when the Ta layer thickness is reduced, indicating that there are two competing effects contributing to it. Our results illustrate that the presence of atomically thin metals can profoundly change the landscape for controlling magnetic moments in magnetic heterostructures electrically.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Figure 1: Experimental set-up and the magnetic properties of the Ta and CoFeB wedge films.
Figure 2: Second-harmonic signals illustrating the variation in the effective field under different conditions.
Figure 3: Ta and CoFeB thickness dependence of the transverse effective field.
Figure 4: Ta and CoFeB thickness dependence of the longitudinal effective field.
Figure 5: Ratio of the longitudinal and transverse effective fields.

Similar content being viewed by others

References

  1. Miron, I. M. et al. Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection. Nature 476, 189–193 (2011).

    Article  CAS  Google Scholar 

  2. Liu, L. et al. Spin-torque switching with the giant spin Hall effect of tantalum. Science 336, 555–558 (2012).

    Article  CAS  Google Scholar 

  3. Miron, I. M. et al. Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer. Nature Mater. 9, 230–234 (2010).

    Article  Google Scholar 

  4. Miron, I. M. et al. Fast current-induced domain-wall motion controlled by the Rashba effect. Nature Mater. 10, 419–423 (2011).

    Article  CAS  Google Scholar 

  5. Brataas, A., Kent, A. D. & Ohno, H. Current-induced torques in magnetic materials. Nature Mater. 11, 372–381 (2012).

    Article  CAS  Google Scholar 

  6. Bychkov, Y. A. & Rashba, E. I. Oscillatory effects and the magnetic-susceptibility of carriers in inversion-layers. J. Phys. C 17, 6039–6045 (1984).

    Article  Google Scholar 

  7. Edelstein, V. M. Spin polarization of conduction electrons induced by electric-current in 2-dimensional asymmetric electron-systems. Solid State Commun. 73, 233–235 (1990).

    Article  Google Scholar 

  8. Tan, S. G., Jalil, M. B. A. & Liu, X-J. Local spin dynamic arising from the non-perturbative SU(2) gauge field of the spin orbit effect. Preprint at http://arxiv.org/abs/0705.3502v1 (2007).

  9. Manchon, A. & Zhang, S. Theory of nonequilibrium intrinsic spin torque in a single nanomagnet. Phys. Rev. B 78, 212405 (2008).

    Article  Google Scholar 

  10. Obata, K. & Tatara, G. Current-induced domain wall motion in Rashba spin-orbit system. Phys. Rev. B 77, 214429 (2008).

    Article  Google Scholar 

  11. Kim, K-W., Seo, S-M., Ryu, J., Lee, K-J. & Lee, H-W. Magnetization dynamics induced by in-plane currents in ultrathin magnetic nanostructures with Rashba spin-orbit coupling. Phys. Rev. B 85, 180404 (2012).

    Article  Google Scholar 

  12. Wang, X. & Manchon, A. Diffusive spin dynamics in ferromagnetic thin films with a Rashba interaction. Phys. Rev. Lett. 108, 117201 (2012).

    Article  Google Scholar 

  13. Pesin, D. A. & MacDonald, A. H. Quantum kinetic theory of current-induced torques in Rashba ferromagnets. Phys. Rev. B 86, 014416 (2012).

    Article  Google Scholar 

  14. Pi, U. H. et al. Tilting of the spin orientation induced by Rashba effect in ferromagnetic metal layer. Appl. Phys. Lett. 97, 162507 (2010).

    Article  Google Scholar 

  15. Jungwirth, T., Wunderlich, J. & Olejnik, K. Spin Hall effect devices. Nature Mater. 11, 382–390 (2012).

    Article  CAS  Google Scholar 

  16. Manchon, A. Spin Hall effect versus Rashba torque: A diffusive approach. Preprint at http://arxiv.org/abs/1204.4869 (2012).

  17. Seo, S. M., Kim, K. W., Ryu, J., Lee, H. W. & Lee, K. J. Current-induced motion of a transverse magnetic domain wall in the presence of spin Hall effect. Appl. Phys. Lett. 101, 022405 (2012).

    Article  Google Scholar 

  18. Suzuki, T. et al. Current-induced effective field in perpendicularly magnetized Ta/CoFeB/MgO wire. Appl. Phys. Lett. 98, 142505 (2011).

    Article  Google Scholar 

  19. Ikeda, S. et al. A perpendicular-anisotropy CoFeB|MgO magnetic tunnel junction. Nature Mater. 9, 721–724 (2010).

    Article  CAS  Google Scholar 

  20. Worledge, D. C. et al. Spin torque switching of perpendicular Ta|CoFeB|MgO-based magnetic tunnel junctions. Appl. Phys. Lett. 98, 022501 (2011).

    Article  Google Scholar 

  21. Fukami, S. et al. Current-induced domain wall motion in perpendicularly magnetized CoFeB nanowire. Appl. Phys. Lett. 98, 082504 (2011).

    Article  Google Scholar 

  22. Hayashi, M. et al. Spatial control of magnetic anisotropy for current induced domain wall injection in perpendicularly magnetized CoFeB|MgO nanostructures. Appl. Phys. Lett. 100, 192411 (2012).

    Article  Google Scholar 

  23. Liu, L. Q., Moriyama, T., Ralph, D. C. & Buhrman, R. A. Spin-torque ferromagnetic resonance induced by the spin Hall effect. Phys. Rev. Lett. 106, 036601 (2011).

    Article  Google Scholar 

  24. Morota, M. et al. Indication of intrinsic spin Hall effect in 4d and 5d transition metals. Phys. Rev. B 83, 174405 (2011).

    Article  Google Scholar 

  25. Slonczcwski, J. C. Currents and torques in metallic magnetic multilayers. J. Magn. Magn. Mater. 247, 324–338 (2002).

    Article  Google Scholar 

  26. Oh, S. C. et al. Bias-voltage dependence of perpendicular spin-transfer torque in asymmetric MgO-based magnetic tunnel junctions. Nature Phys. 5, 898–902 (2009).

    Article  CAS  Google Scholar 

  27. Zhang, S., Levy, P. M. & Fert, A. Mechanisms of spin-polarized current-driven magnetization switching. Phys. Rev. Lett. 88, 236601 (2002).

    Article  CAS  Google Scholar 

  28. Sankey, J. C. et al. Measurement of the spin-transfer-torque vector in magnetic tunnel junctions. Nature Phys. 4, 67–71 (2008).

    Article  CAS  Google Scholar 

  29. Kubota, H. et al. Quantitative measurement of voltage dependence of spin-transfer torque in MgO-based magnetic tunnel junctions. Nature Phys. 4, 37–41 (2008).

    Article  CAS  Google Scholar 

  30. Petit, S. et al. Spin-torque influence on the high-frequency magnetization fluctuations in magnetic tunnel junctions. Phys. Rev. Lett. 98, 077203 (2007).

    Article  CAS  Google Scholar 

  31. Li, Z. et al. Perpendicular spin torques in magnetic tunnel junctions. Phys. Rev. Lett. 100, 246602 (2008).

    Article  CAS  Google Scholar 

  32. Albert, F. J., Emley, N. C., Myers, E. B., Ralph, D. C. & Buhrman, R. A. Quantitative study of magnetization reversal by spin-polarized current in magnetic multilayer nanopillars. Phys. Rev. Lett. 89, 226802 (2002).

    Article  CAS  Google Scholar 

  33. Chen, W., Rooks, M. J., Ruiz, N., Sun, J. Z. & Kent, A. D. Spin transfer in bilayer magnetic nanopillars at high fields as a function of free-layer thickness. Phys. Rev. B 74, 144408 (2006).

    Article  Google Scholar 

  34. Stiles, M. D. & Zangwill, A. Anatomy of spin-transfer torque. Phys. Rev. B 66, 014407 (2002).

    Article  Google Scholar 

  35. Shpiro, A., Levy, P. M. & Zhang, S. F. Self-consistent treatment of nonequilibrium spin torques in magnetic multilayers. Phys. Rev. B 67, 104430 (2003).

    Article  Google Scholar 

  36. Zwierzycki, M., Tserkovnyak, Y., Kelly, P. J., Brataas, A. & Bauer, G. E. W. First-principles study of magnetization relaxation enhancement and spin transfer in thin magnetic films. Phys. Rev. B 71, 064420 (2005).

    Article  Google Scholar 

  37. Jalil, M. B. A., Tan, S. G., Law, R. & Chung, N. L. Layer thickness and angular dependence of spin transfer torque in ferromagnetic trilayers. J. Appl. Phys. 101, 124314 (2007).

    Article  Google Scholar 

  38. Wang, S., Xu, Y. & Xia, K. First-principles study of spin-transfer torques in layered systems with noncollinear magnetization. Phys. Rev. B 77, 184430 (2008).

    Article  Google Scholar 

  39. Urazhdin, S., Loloee, R. & Pratt, W. P. Noncollinear spin transport in magnetic multilayers. Phys. Rev. B 71, 100401 (2005).

    Article  Google Scholar 

  40. Taniguchi, T., Yakata, S., Imamura, H. & Ando, Y. Penetration depth of transverse spin current in ferromagnetic metals. IEEE Trans. Magn. 44, 2636–2639 (2008).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors acknowledge helpful discussions with H-W. Lee, K-J. Lee and T. Taniguchi. We thank M. Kodzuka, T. Ohkubo and K. Hono for their support on film characterization. This work was partly supported by the Japan Society for the Promotion of Science (JSPS) though its ‘Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST program)’.

Author information

Authors and Affiliations

Authors

Contributions

M.H. planned the study. J.K., M.H., M.Y. and H.O. wrote the manuscript. J.S. performed film deposition and film characterization, M.H. fabricated the devices. J.K. carried out the measurements and analysed the data with the help of M.H., M.Y., S.F., T.S., S.M. and H.O. All authors discussed the data and commented on the manuscript.

Corresponding author

Correspondence to Masamitsu Hayashi.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 756 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kim, J., Sinha, J., Hayashi, M. et al. Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. Nature Mater 12, 240–245 (2013). https://doi.org/10.1038/nmat3522

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3522

This article is cited by

Search

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