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
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
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
Similar content being viewed by others
References
Miron, I. M. et al. Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection. Nature 476, 189–193 (2011).
Liu, L. et al. Spin-torque switching with the giant spin Hall effect of tantalum. Science 336, 555–558 (2012).
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).
Miron, I. M. et al. Fast current-induced domain-wall motion controlled by the Rashba effect. Nature Mater. 10, 419–423 (2011).
Brataas, A., Kent, A. D. & Ohno, H. Current-induced torques in magnetic materials. Nature Mater. 11, 372–381 (2012).
Bychkov, Y. A. & Rashba, E. I. Oscillatory effects and the magnetic-susceptibility of carriers in inversion-layers. J. Phys. C 17, 6039–6045 (1984).
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).
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).
Manchon, A. & Zhang, S. Theory of nonequilibrium intrinsic spin torque in a single nanomagnet. Phys. Rev. B 78, 212405 (2008).
Obata, K. & Tatara, G. Current-induced domain wall motion in Rashba spin-orbit system. Phys. Rev. B 77, 214429 (2008).
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).
Wang, X. & Manchon, A. Diffusive spin dynamics in ferromagnetic thin films with a Rashba interaction. Phys. Rev. Lett. 108, 117201 (2012).
Pesin, D. A. & MacDonald, A. H. Quantum kinetic theory of current-induced torques in Rashba ferromagnets. Phys. Rev. B 86, 014416 (2012).
Pi, U. H. et al. Tilting of the spin orientation induced by Rashba effect in ferromagnetic metal layer. Appl. Phys. Lett. 97, 162507 (2010).
Jungwirth, T., Wunderlich, J. & Olejnik, K. Spin Hall effect devices. Nature Mater. 11, 382–390 (2012).
Manchon, A. Spin Hall effect versus Rashba torque: A diffusive approach. Preprint at http://arxiv.org/abs/1204.4869 (2012).
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).
Suzuki, T. et al. Current-induced effective field in perpendicularly magnetized Ta/CoFeB/MgO wire. Appl. Phys. Lett. 98, 142505 (2011).
Ikeda, S. et al. A perpendicular-anisotropy CoFeB|MgO magnetic tunnel junction. Nature Mater. 9, 721–724 (2010).
Worledge, D. C. et al. Spin torque switching of perpendicular Ta|CoFeB|MgO-based magnetic tunnel junctions. Appl. Phys. Lett. 98, 022501 (2011).
Fukami, S. et al. Current-induced domain wall motion in perpendicularly magnetized CoFeB nanowire. Appl. Phys. Lett. 98, 082504 (2011).
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).
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).
Morota, M. et al. Indication of intrinsic spin Hall effect in 4d and 5d transition metals. Phys. Rev. B 83, 174405 (2011).
Slonczcwski, J. C. Currents and torques in metallic magnetic multilayers. J. Magn. Magn. Mater. 247, 324–338 (2002).
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).
Zhang, S., Levy, P. M. & Fert, A. Mechanisms of spin-polarized current-driven magnetization switching. Phys. Rev. Lett. 88, 236601 (2002).
Sankey, J. C. et al. Measurement of the spin-transfer-torque vector in magnetic tunnel junctions. Nature Phys. 4, 67–71 (2008).
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).
Petit, S. et al. Spin-torque influence on the high-frequency magnetization fluctuations in magnetic tunnel junctions. Phys. Rev. Lett. 98, 077203 (2007).
Li, Z. et al. Perpendicular spin torques in magnetic tunnel junctions. Phys. Rev. Lett. 100, 246602 (2008).
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).
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).
Stiles, M. D. & Zangwill, A. Anatomy of spin-transfer torque. Phys. Rev. B 66, 014407 (2002).
Shpiro, A., Levy, P. M. & Zhang, S. F. Self-consistent treatment of nonequilibrium spin torques in magnetic multilayers. Phys. Rev. B 67, 104430 (2003).
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).
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).
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).
Urazhdin, S., Loloee, R. & Pratt, W. P. Noncollinear spin transport in magnetic multilayers. Phys. Rev. B 71, 100401 (2005).
Taniguchi, T., Yakata, S., Imamura, H. & Ando, Y. Penetration depth of transverse spin current in ferromagnetic metals. IEEE Trans. Magn. 44, 2636–2639 (2008).
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
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
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Supplementary information
Supplementary Information
Supplementary Information (PDF 756 kb)
Rights 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
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nmat3522
This article is cited by
-
cmtj: Simulation package for analysis of multilayer spintronic devices
npj Computational Materials (2023)
-
Design of high-speed, low-power non-volatile master slave flip flop (NVMSFF) for memory registers designs
Applied Nanoscience (2023)
-
Sign reversal and manipulation of anomalous Hall resistivity in facing-target sputtered Pt/Mn4N bilayers
Rare Metals (2023)
-
Efficient spin–orbit torque in magnetic trilayers using all three polarizations of a spin current
Nature Electronics (2022)
-
Ultrahigh efficient spin orbit torque magnetization switching in fully sputtered topological insulator and ferromagnet multilayers
Scientific Reports (2022)