Spintronics relies on magnetization switching through current-induced spin torques. However, because spin transfer torque for ferromagnets is a surface torque, a large switching current is required for a thick, thermally stable ferromagnetic cell, and this remains a fundamental obstacle for high-density non-volatile applications with ferromagnets. Here, we report a long spin coherence length and associated bulk-like torque characteristics in an antiferromagnetically coupled ferrimagnetic multilayer. We find that a transverse spin current can pass through >10-nm-thick ferrimagnetic Co/Tb multilayers, whereas it is entirely absorbed by a 1-nm-thick ferromagnetic Co/Ni multilayer. We also find that the switching efficiency of Co/Tb multilayers partially reflects a bulk-like torque characteristic, as it increases with ferrimagnet thickness up to 8 nm and then decreases, in clear contrast to the 1/thickness dependence of ferromagnetic Co/Ni multilayers. Our results on antiferromagnetically coupled systems will invigorate research towards the development of energy-efficient spintronics.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data supporting the findings of this study are available within the paper and other findings of this study are available from the corresponding author upon reasonable request.
Slonczewski, J. C. Current-driven excitation of magnetic multilayers. J. Magn. Magn. Mater. 159, L1–L7 (1996).
Berger, L. Emission of spin waves by a magnetic multilayer traversed by a current. Phys. Rev. B 54, 9353–9358 (1996).
Tsoi, M. et al. Excitation of a magnetic multilayer by an electric current. Phys. Rev. Lett. 80, 4281–4284 (1998).
Myers, E. B., Ralph, D. C., Katine, J. A., Louie, R. N. & Buhrman, R. A. Current-induced switching of domains in magnetic multilayer devices. Science 285, 867–870 (1999).
Waintal, X., Myers, E. B., Brouwer, P. W. & Ralph, D. C. Role of spin-dependent interface scattering in generating current-induced torques in magnetic multilayers. Phys. Rev. B 62, 12317–12327 (2000).
Stiles, M. D. & Zangwill, A. Anatomy of spin-transfer torque. Phys. Rev. B 66, 014407 (2002).
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).
Kovalev, A. A., Bauer, G. E. W. & Brataas, A. Perpendicular spin valves with ultrathin ferromagnetic layers: magnetoelectronic circuit investigation of finite-size effects. Phys. Rev. B 73, 054407 (2006).
Núñez, A. S., Duine, R. A., Haney, P. & MacDonald, A. H. Theory of spin torques and giant magnetoresistance in antiferromagnetic metals. Phys. Rev. B 73, 214426 (2006).
Haney, P. M. & MacDonald, A. H. Current-induced torques due to compensated antiferromagnets. Phys. Rev. Lett. 100, 196801 (2008).
Xu, Y., Wang, S. & Xia, K. Spin-transfer torques in antiferromagnetic metals from first principles. Phys. Rev. Lett. 100, 226602 (2008).
Wei, Z. et al. Changing exchange bias in spin valves with an electric current. Phys. Rev. Lett. 98, 116603 (2007).
Urazhdin, S. & Anthony, N. Effect of polarized current on the magnetic state of an antiferromagnet. Phys. Rev. Lett. 99, 046602 (2007).
Wadley, P. et al. Electrical switching of an antiferromagnet. Science 351, 587–590 (2016).
Mishra, R. et al. Anomalous current-induced spin torques in ferrimagnets near compensation. Phys. Rev. Lett. 118, 167201 (2017).
Finley, J. & Liu, L. Spin–orbit-torque efficiency in compensated ferrimagnetic cobalt-terbium alloys. Phys. Rev. Appl. 6, 054001 (2016).
Roschewsky, N., Lambert, C.-H. & Salahuddin, S. Spin–orbit torque switching of ultralarge-thickness ferrimagnetic GdFeCo. Phys. Rev. B 96, 064406 (2017).
Ueda, K., Mann, M., de Brouwer, P. W. P., Bono, D. & Beach, G. S. D. Temperature dependence of spin–orbit torques across the magnetic compensation point in a ferrimagnetic TbCo alloy film. Phys. Rev. B 96, 064410 (2017).
Fert, A., 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).
Kim, K.-J. et al. Fast domain wall motion in the vicinity of the angular momentum compensation temperature of ferrimagnets. Nat. Mater. 16, 1187–1192 (2017).
Hebler, B., Hassdenteufel, A., Reinhardt, P., Karl, H. & Albrecht, M. Ferrimagnetic Tb–Fe alloy thin films: composition and thickness dependence of magnetic properties and all-optical switching. Front. Mater. 3, 8 (2016).
Garello, K. et al. Symmetry and magnitude of spin–orbit torques in ferromagnetic heterostructures. Nat. Nanotech. 8, 587–593 (2013).
Kim, J. et al. Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. Nat. Mater. 12, 240–245 (2013).
Jamali, M. et al. Spin–orbit torques in Co/Pd multilayer nanowires. Phys. Rev. Lett. 111, 246602 (2013).
Qiu, X. et al. Angular and temperature dependence of current induced spin–orbit effective fields in Ta/CoFeB/MgO nanowires. Sci. Rep. 4, 4491 (2014).
Lee, O. J. et al. Central role of domain wall depinning for perpendicular magnetization switching driven by spin torque from the spin Hall effect. Phys. Rev. B 89, 024418 (2014).
Brataas, A., Kent, A. D. & Ohno, H. Current-induced torques in magnetic materials. Nat. Mater. 11, 372–381 (2012).
Graves, C. E. et al. Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo. Nat. Mater. 12, 293–298 (2013).
Chimata, R. et al. All-thermal switching of amorphous Gd–Fe alloys: analysis of structural properties and magnetization dynamics. Phys. Rev. B 92, 094411 (2015).
Harris, V. G., Aylesworth, K. D., Das, B. N., Elam, W. T. & Koon, N. C. Structural origins of magnetic anisotropy in sputtered amorphous Tb–Fe films. Phys. Rev. Lett. 69, 1939–1942 (1992).
Hufnagel, T. C., Brennan, S., Zschack, P. & Clemens, B. M. Structural anisotropy in amorphous Fe–Tb thin films. Phys. Rev. B 53, 12024–12030 (1996).
Emori, S., Bauer, U., Ahn, S.-M., Martinez, E. & Beach, G. S. D. Current-driven dynamics of chiral ferromagnetic domain walls. Nat. Mater. 12, 611–616 (2013).
Ryu, K.-S., Thomas, L., Yang, S.-H. & Parkin, S. Chiral spin torque at magnetic domain walls. Nat. Nanotech. 8, 527–533 (2013).
Sampaio, J., Cros, V., Rohart, S., Thiaville, A. & Fert, A. Nucleation, stability and current-induced motion of isolated magnetic skyrmions in nanostructures. Nat. Nanotech. 8, 839–844 (2013).
The authors acknowledge discussions with P.M. Haney. This research was supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore, under its Competitive Research Programme (CRP award no. NRFCRP12-2013-01). K.-J.L. was supported by the National Research Foundation of Korea (NRF-2015M3D1A1070465 and NRF-2017R1A2B2006119) and the KIST Institutional Program (project no. 2V05750) and Samsung Research Funding Center of Samsung Electronics under project no. SRFCMA1702-02.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Yu, J., Bang, D., Mishra, R. et al. Long spin coherence length and bulk-like spin–orbit torque in ferrimagnetic multilayers. Nature Mater 18, 29–34 (2019). https://doi.org/10.1038/s41563-018-0236-9
IEEE Transactions on Magnetics (2021)
Journal of Physics D: Applied Physics (2021)
Physical Review B (2021)
IEEE Transactions on Magnetics (2021)
Physical Review B (2020)