Two-terminal spin–orbit torque magnetoresistive random access memory

Abstract

Spin-transfer torque magnetoresistive random access memory (STT-MRAM) is an attractive alternative to existing random access memory technologies due to its non-volatility, fast operation and high endurance. However, STT-MRAM does have limitations, including the stochastic nature of the STT-switching and a high critical switching current, which makes it unsuitable for ultrafast operation in the nanosecond and subnanosecond regimes. Spin–orbit torque (SOT) switching, which relies on the torque generated by an in-plane current, has the potential to overcome these limitations. However, SOT-MRAM cells studied so far use a three-terminal structure to apply the in-plane current, which increases the size of the cells. Here we report a two-terminal SOT-MRAM cell based on a CoFeB/MgO magnetic tunnel junction pillar on an ultrathin and narrow Ta underlayer. In this device, in-plane and out-of-plane currents are simultaneously generated on application of a voltage, and we demonstrate that the switching mechanism is dominated by SOT.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Characterization of two-terminal SOT devices.
Fig. 2: Current-induced magnetization switching in two-terminal SOT devices.
Fig. 3: Pulse width and wTa dependences of the critical current in the two-terminal SOT switching.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. 1.

    International Technology Roadmap for Semiconductors (ITRS, accessed 17 June 2018); http://www.itrs2.net/

  2. 2.

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

    Article  Google Scholar 

  3. 3.

    Worledge, D. C., Hu, G., Abraham, D. W., Trouilloud, P. L. & Brown, S. Development of perpendicularly magnetized Ta|CoFeB|MgO-based tunnel junctions at IBM (invited). J. Appl. Phys. 115, 172601 (2014).

    Article  Google Scholar 

  4. 4.

    Sato, H. et al. MgO/CoFeB/Ta/CoFeB/MgO recording structure in magnetic tunnel junctions with perpendicular easy axis. IEEE. Trans. Magn. 49, 4437–4440 (2013).

    Article  Google Scholar 

  5. 5.

    Yuasa, S., Hono, K., Hu, G. & Worledge, D. C. Materials for spin-transfer-torque magnetoresistive random-access memory. MRS. Bull. 43, 352–357 (2018).

    Article  Google Scholar 

  6. 6.

    Dieny, B., Goldfarb, R. B. & Lee, K.-J. Introduction to Magnetic Random-Access Memory (Wiley-IEEE Press, New York, 2016).

  7. 7.

    Zhang, S. Spin Hall effect in the presence of spin diffusion. Phys. Rev. Lett. 85, 393–396 (2000).

    Article  Google Scholar 

  8. 8.

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

    Article  Google Scholar 

  9. 9.

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

    Article  Google Scholar 

  10. 10.

    Liu, L., Lee, O. J., Gudmundsen, T. J., Ralph, D. C. & Buhrman, R. A. Current-induced switching of perpendicularly magnetized magnetic layers using spin torque from the spin Hall effect. Phys. Rev. Lett. 109, 096602 (2012).

    Article  Google Scholar 

  11. 11.

    Kim, J. et al. Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. Nat. Mater. 12, 240–245 (2013).

    Article  Google Scholar 

  12. 12.

    Garello, K. et al. Ultrafast magnetization switching by spin–orbit torques. Appl. Phys. Lett. 105, 212402 (2014).

    Article  Google Scholar 

  13. 13.

    Manipatruni, S., Nikonov, D. E. & Young, I. A. Beyond CMOS computing with spin and polarization. Nat. Phys. 14, 338–343 (2018).

    Article  Google Scholar 

  14. 14.

    Brosse, J. K. D., Liu, L. & Worledge, D. Spin Hall effect assisted spin transfer torque magnetic random access memory. US patent 20140264511A1 (2014).

  15. 15.

    Wang, Z., Zhao, W., Deng, E., Klein, J.-O. & Chappert, C. Perpendicular-anisotropy magnetic tunnel junction switched by spin-Hall-assisted spin-transfer torque. J. Phys. D 48, 065001 (2015).

    Article  Google Scholar 

  16. 16.

    van den Brink, A. et al. Spin-Hall-assisted magnetic random access memory. Appl. Phys. Lett. 104, 012403 (2014).

    Article  Google Scholar 

  17. 17.

    Lee, K.-S., Lee, S.-W., Min, B.-C. & Lee, K.-J. Threshold current for switching of a perpendicular magnetic layer induced by spin Hall effect. Appl. Phys. Lett. 102, 112410 (2013).

    Article  Google Scholar 

  18. 18.

    Cubukcu, M. et al. Ultra-fast perpendicular spin–orbit torque MRAM. IEEE. Trans. Magn. 54, 9300204 (2018).

    Article  Google Scholar 

  19. 19.

    Zhang, C., Fukami, S., Sato, H., Matsukura, F. & Ohno, H. Spin–orbit torque induced magnetization switching in nano-scale Ta/CoFeB/MgO. Appl. Phys. Lett. 107, 012401 (2015).

    Article  Google Scholar 

  20. 20.

    Lee, K.-S., Lee, S.-W., Min, B.-C. & Lee, K.-J. Thermally activated switching of perpendicular magnet by spin–orbit spin torque. Appl. Phys. Lett. 104, 072413 (2014).

    Article  Google Scholar 

  21. 21.

    Taniguchi, T., Mitani, S. & Hayashi, M. Critical current destabilizing perpendicular magnetization by the spin Hall effect. Phys. Rev. B 92, 024428 (2015).

    Article  Google Scholar 

  22. 22.

    Wang, M. et al. Field-free switching of perpendicular magnetic tunnel junction by the interplay of spin orbit and spin transfer torques. Preprint at https://arXiv.org/abs/1806.06174 (2018).

  23. 23.

    Yu, G. et al. Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields. Nat. Nanotech. 9, 548–554 (2014).

    Article  Google Scholar 

  24. 24.

    Fukami, S., Zhang, C., DuttaGupta, S., Kurenkov, A. & Ohno, H. Magnetization switching by spin–orbit torque in an antiferromagnet–ferromagnet bilayer system. Nat. Mater. 15, 535–541 (2016).

    Article  Google Scholar 

  25. 25.

    You, L. et al. Switching of perpendicularly polarized nanomagnets with spin orbit torque without an external magnetic field by engineering a tilted anisotropy. Proc. Natl Acad. Sci. USA 112, 10310–10315 (2015).

    Article  Google Scholar 

  26. 26.

    Hsu, W.-H., Bell, R. & Victora, R.H. Ultra-low write energy composite free layer spin-orbit torque MRAM. IEEE Tran. Mag. https://doi.org/10.1109/TMAG.2018.2847235 (2018).

Download references

Acknowledgements

S.X.W. thanks TSMC, Stanford SystemX Alliance, Stanford Center for Magnetic Nanotechnology, and the NSF Center for Energy Efficient Electronics Science (E3S) for financial support. N.S. thanks Funai Foundation for Information Technology for the overseas scholarship. This work was supported in part by ASCENT, one of six centres in JUMP, a Semiconductor Research Corporation (SRC) programme sponsored by DARPA. The experimental work has benefited from the equipment and tools at the Stanford Nanofabrication Facility, Stanford Nano Shared Facilities, and Michigan Lurie Nanofabrication Facility (LNF), which are supported by the National Science Foundation (NSF).

Author information

Affiliations

Authors

Contributions

N.S., R.M.W. and S.X.W. conceived the experiments, N.S. and F.X. conducted the experiments, and N.S., C.B. and S.X.W. analysed the results. All authors reviewed the manuscript.

Corresponding author

Correspondence to Shan X. Wang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Notes 1–5 and Supplementary Figures 1–10

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sato, N., Xue, F., White, R.M. et al. Two-terminal spin–orbit torque magnetoresistive random access memory. Nat Electron 1, 508–511 (2018). https://doi.org/10.1038/s41928-018-0131-z

Download citation

Further reading

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