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Time-resolved measurement of spin-transfer-driven ferromagnetic resonance and spin torque in magnetic tunnel junctions


The bias dependence of the torque that a spin-polarized current exerts on ferromagnetic elements is important for understanding fundamental spin physics in magnetic devices and for applications. Several experimental techniques have been introduced in recent years in attempts to measure spin-transfer torque in magnetic tunnel junctions. However, these techniques have provided only indirect measures of the torque and their results regarding bias dependence are qualitatively and quantitatively inconsistent. Here we demonstrate that spin torque in magnetic tunnel junctions can be measured directly by using time-domain techniques to detect resonant magnetic precession in response to an oscillating spin torque. The technique is accurate in the high-bias regime relevant for applications, and because it detects directly small-angle linear-response magnetic dynamics caused by spin torque it is relatively immune to artefacts affecting competing techniques. At high bias we find that the spin-torque vector differs markedly from the simple lowest-order Taylor series approximations commonly assumed.

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Figure 1: Overview of the experiment.
Figure 2: Time-resolved measurements of spin-torque-driven magnetic resonance.
Figure 3: Measured bias dependence of the spin-transfer torque vector.


  1. Slonczewski, J. C. Current-driven excitation of magnetic multilayers. J. Magn. Magn. Mater. 159, L1–L7 (1996).

    Article  ADS  Google Scholar 

  2. Berger, L. Emission of spin waves by a magnetic multilayer traversed by a current. Phys. Rev. B 54, 9353–9358 (1996).

    Article  ADS  Google Scholar 

  3. Ralph, D. C. & Stiles, M. D. Spin transfer torques. J. Magn. Magn. Mater. 320, 1190–1216 (2008).

    Article  ADS  Google Scholar 

  4. Katine, J. A. & Fullerton, E. E. Device implications of spin-transfer torques. J. Magn. Magn. Mater. 320, 1217–1226 (2008).

    Article  ADS  Google Scholar 

  5. Tulapurkar, A. A. et al. Spin-torque diode effect in magnetic tunnel junctions. Nature 438, 339–342 (2005).

    Article  ADS  Google Scholar 

  6. Sankey, J. C. et al. Spin-transfer-driven ferromagnetic resonance of individual nanomagnets. Phys. Rev. Lett. 96, 227601 (2006).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  8. 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  ADS  Google Scholar 

  9. Wang, C. et al. Bias and angular dependence of spin-transfer torque in magnetic tunnel junctions. Phys. Rev. B 79, 224416 (2009).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  11. 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  ADS  Google Scholar 

  12. Devolder, T. et al. Direct measurement of current-induced fieldlike torque in magnetic tunnel junctions. J. Appl. Phys. 105, 113924 (2009).

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  14. Petit, S. et al. Influence of spin-transfer torque on thermally activated ferromagnetic resonance excitations in magnetic tunnel junctions. Phys. Rev. B 78, 184420 (2008).

    Article  ADS  Google Scholar 

  15. Deac, A. M. et al. Bias-driven high-power microwave emission from MgO-based tunnel magnetoresistance devices. Nature Phys. 4, 803–809 (2008).

    Article  ADS  Google Scholar 

  16. Jung, M. H., Park, S., You, C-Y. & Yuasa, S. Bias-dependences of in-plane and out-of-plane spin-transfer torques in symmetric MgO-based magnetic tunnel junctions. Phys. Rev. B 81, 134419 (2010).

    Article  ADS  Google Scholar 

  17. Heinonen, O. G., Stokes, S. W. & Yiet, J. Y. Perpendicular spin torque in magnetic tunnel junctions. Phys. Rev. Lett. 105, 066602 (2010).

    Article  ADS  Google Scholar 

  18. Polianski, M. L. & Brouwer, P. W. Current-induced transverse spin-wave instability in a thin nanomagnet. Phys. Rev. Lett. 92, 026602 (2004).

    Article  ADS  Google Scholar 

  19. Stiles, M. D., Xiao, J. & Zangwill, A. Phenomenological theory of current-induced magnetization precession. Phys. Rev. B 69, 054408 (2004).

    Article  ADS  Google Scholar 

  20. Houssameddine, D. et al. Spin transfer induced coherent microwave emission with large power from nanoscale MgO tunnel junctions. Appl. Phys. Lett. 93, 022505 (2008).

    Article  ADS  Google Scholar 

  21. Slonczewski, J. C. & Sun, J. Z. Theory of voltage-driven current and torque in magnetic tunnel junctions. J. Magn. Magn. Mater. 310, 169–175 (2007).

    Article  ADS  Google Scholar 

  22. Kittel, C. Introduction to Solid State Physics 7th edn, 505 (John Wiley, 1996).

    MATH  Google Scholar 

  23. Slonczewski, J. C. Currents, torques, and polarization factors in magnetic tunnel junctions. Phys. Rev. B 71, 024411 (2005).

    Article  ADS  Google Scholar 

  24. Theodonis, I., Kioussis, N., Kalitsov, A., Chshiev, M. & Butler, W. H. Anomalous bias dependence of spin torque in magnetic tunnel junctions. Phys. Rev. Lett. 97, 237205 (2006).

    Article  ADS  Google Scholar 

  25. Wilczynski, M., Barnas, J. & Swirkowiz, R. Free-electron model of current-induced spin-transfer torque in magnetic tunnel junctions. Phys. Rev. B 77, 054434 (2008).

    Article  ADS  Google Scholar 

  26. Xiao, J., Bauer, G. E. W. & Brataas, A. Spin-transfer torque in magnetic tunnel junctions: scattering theory. Phys. Rev. B 77, 224419 (2008).

    Article  ADS  Google Scholar 

  27. Manchon, A., Zhang, S. & Lee, K-J. Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence. Phys. Rev. B 82, 174420 (2008).

    Article  ADS  Google Scholar 

  28. Heiliger, C. & Stiles, M. D. Ab initio studies of the spin-transfer torque in magnetic tunnel junctions. Phys. Rev. Lett. 100, 186805 (2008).

    Article  ADS  Google Scholar 

  29. Li, Z. & Zhang, S. Thermally assisted magnetization reversal in the presence of a spin-transfer torque. Phys. Rev. B 69, 134416 (2004).

    Article  ADS  Google Scholar 

  30. Fuchs, G. D. et al. Adjustable spin torque in magnetic tunnel junctions with two fixed layers. Appl. Phys. Lett. 86, 152509 (2005).

    Article  ADS  Google Scholar 

  31. Diao, Z. et al. Spin transfer switching and spin polarization in magnetic tunnel junctions with MgO and AlOx barriers. Appl. Phys. Lett. 87, 232502 (2005).

    Article  ADS  Google Scholar 

  32. Ikeda, S. et al. Magnetic tunnel junctions for spintronic memories and beyond. IEEE Trans. Electron Devices 54, 991–1002 (2007).

    Article  ADS  Google Scholar 

  33. Yoshikawa, M. et al. Estimation of spin transfer torque effect and thermal activation effect on magnetization reversal in CoFeB/MgO/CoFeB magnetoresistive tunneling junctions. J. Appl. Phys. 101, 09A511 (2007).

    Article  Google Scholar 

  34. Devolder, T. et al. Single-shot time-resolved measurement of nanosecond-scale spin-transfer induced switching: stochastic versus deterministic aspects. Phys. Rev. Lett. 100, 057206 (2008).

    Article  ADS  Google Scholar 

  35. Lee, K. & Kang, S. H. Design consideration of magnetic tunnel junctions for reliable high-temperature operation of STT-MRAM. IEEE Trans. Magn. 46, 1537–1540 (2010).

    Article  ADS  Google Scholar 

  36. Chen, E. et al. Advances and future prospects of spin-transfer torque random access memory. IEEE Trans. Magn. 46, 1873–1878 (2010).

    Article  ADS  Google Scholar 

  37. Chen, W., de Loubens, G., Beaujour, J-M. L., Sun, J. Z. & Kent, A. D. Spin-torque driven ferromagnetic resonance in a nonlinear regime. Appl. Phys. Lett. 95, 172513 (2009).

    Article  ADS  Google Scholar 

  38. Rippard, W. H. et al. Injection locking and phase control of spin transfer nano-oscillators. Phys. Rev. Lett. 95, 067203 (2005).

    Article  ADS  Google Scholar 

  39. Grollier, J., Cros, V. & Fert, A. Synchronization of spin-transfer oscillators driven by stimulated microwave currents. Phys. Rev. B 73, 060409 (2006).

    Article  ADS  Google Scholar 

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We thank D. Mauri of Hitachi Global Storage Technologies (now at Western Digital Corp.) for providing the junction thin film stacks that we used to fabricate the tunnel junctions. Cornell acknowledges support from ARO, ONR, DARPA, NSF (DMR-1010768), and the NSF/NSEC program through the Cornell Center for Nanoscale Systems. We also acknowledge NSF support through use of the Cornell Nanofabrication Facility/NNIN and the Cornell Center for Materials Research facilities.

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Authors and Affiliations



C.W. played the primary role in designing and performing the experiment and analysing the data. J.A.K. led the sample fabrication. Y-T.C. assisted in the measurements. All of the authors contributed to the data analysis and the preparation of the manuscript.

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Correspondence to Daniel C. Ralph.

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The authors declare no competing financial interests.

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Wang, C., Cui, YT., Katine, J. et al. Time-resolved measurement of spin-transfer-driven ferromagnetic resonance and spin torque in magnetic tunnel junctions. Nature Phys 7, 496–501 (2011).

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