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.

A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction

Nature Materials volume 9, pages 721–724 (2010)Cite this article

Subjects

Abstract

Magnetic tunnel junctions (MTJs) with ferromagnetic electrodes possessing a perpendicular magnetic easy axis are of great interest as they have a potential for realizing next-generation high-density non-volatile memory and logic chips with high thermal stability and low critical current for current-induced magnetization switching1,2,3. To attain perpendicular anisotropy, a number of material systems have been explored as electrodes, which include rare-earth/transition-metal alloys4,5, L10-ordered (Co, Fe)–Pt alloys3,6,7 and Co/(Pd, Pt) multilayers1,8,9,10. However, none of them so far satisfy high thermal stability at reduced dimension, low-current current-induced magnetization switching and high tunnel magnetoresistance ratio all at the same time. Here, we use interfacial perpendicular anisotropy between the ferromagnetic electrodes and the tunnel barrier of the MTJ by employing the material combination of CoFeB–MgO, a system widely adopted to produce a giant tunnel magnetoresistance ratio in MTJs with in-plane anisotropy11,12,13. This approach requires no material other than those used in conventional in-plane-anisotropy MTJs. The perpendicular MTJs consisting of Ta/CoFeB/MgO/CoFeB/Ta show a high tunnel magnetoresistance ratio, over 120%, high thermal stability at dimension as low as 40 nm diameter and a low switching current of 49 μA.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

Buy

All prices are NET prices.

Figure 1: MTJ structure.
Figure 2: In-plane and out-of-plane magnetization curves for CoFeB/MgO.
Figure 3: FMR spectra for CoFeB/MgO and obtained material parameters.
Figure 4: TMR for MTJs with a 150 nm diameter.
Figure 5: TMR and CIMS for an MTJ with a 40 nm diameter.

References

  1. Mangin, S. et al. Current-induced magnetization reversal in nanopillars with perpendicular anisotropy. Nature Mater. 5, 210–215 (2006).

    CAS  Article  Google Scholar 

  2. Meng, H. & Wang, J. P. Spin transfer in nanomagnetic devices with perpendicular anisotropy. Appl. Phys. Lett. 88, 172506 (2006).

    Article  Google Scholar 

  3. Kishi, T. et al. Lower-current and fast switching of a perpendicular TMR for high speed and high density spin-transfer-torque MRAM. IEDM Tech. Dig. 309–312 (2008).

  4. Nishimura, N. et al. Magnetic tunnel junction device with perpendicular magnetization films for high-density magnetic random access memory. J. Appl. Phys. 91, 5246–5249 (2002).

    CAS  Article  Google Scholar 

  5. Ohmori, H., Hatori, T. & Nakagawa, S. Perpendicular magnetic tunnel junction with tunnelling magnetoresistance ratio of 64% using MgO(100) barrier layer prepared at room temperature. J. Appl. Phys. 103, 07A911 (2008).

    Article  Google Scholar 

  6. Yoshikawa, M. et al. Tunnel magnetoresistance over 100% in MgO-based magnetic tunnel junction films with perpendicular magnetic L10-FePt electrodes. IEEE Trans. Magn. 44, 2573–2576 (2008).

    CAS  Article  Google Scholar 

  7. Kim, G., Sakuraba, Y., Oogane, M., Ando, Y. & Miyazaki, T. Tunnelling magnetoresistance of magnetic tunnel junctions using perpendicular magnetization L10-CoPt electrodes. Appl. Phys. Lett. 92, 172502 (2008).

    Article  Google Scholar 

  8. Carvello, B. et al. Sizable room-temperature magnetoresistance in cobalt based magnetic tunnel junctions with out-of-plane anisotropy. Appl. Phys. Lett. 92, 102508 (2008).

    Article  Google Scholar 

  9. Park, J-H. et al. Co/Pt multilayer based magnetic tunnel junctions using perpendicular magnetic anisotropy. J. Appl. Phys. 103, 07A917 (2008).

    Article  Google Scholar 

  10. Mizunuma, K. et al. MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers. Appl. Phys. Lett. 95, 232516 (2009).

    Article  Google Scholar 

  11. Parkin, S. S. P. et al. Giant tunnel magnetoresistance at room temperature with MgO(100) tunnel barrier. Nature Mater. 3, 862–867 (2004).

    CAS  Article  Google Scholar 

  12. Yuasa, S., Nagahama, T., Fukushima, A., Suzuki, Y. & Ando, K. Giant room-temperature magnetoresistance Fe/MgO/Fe magnetic tunnel junctions. Nature Mater. 3, 868–871 (2004).

    CAS  Article  Google Scholar 

  13. Ikeda, S. et al. Tunnel magnetoresistance of 604% at 300 K by suppression of Ta diffusion in CoFeB/MgO/CoFeB/ pseudo-spin-valves annealed at high temperature. Appl. Phys. Lett. 93, 082508 (2008).

    Article  Google Scholar 

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

    CAS  Article  Google Scholar 

  15. Ovanov, O. A., Solina, L. V., Demshina, V. A. & Magat, L. M. Determination of the anisotropy constant and saturation magnetization and magnetic properties of powders of an iron-platinum alloy. Phys. Met. Metallogr. 35, 81–85 (1973).

    Google Scholar 

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

    CAS  Article  Google Scholar 

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

    CAS  Article  Google Scholar 

  18. Sakuma, A. First principle calculation of the magnetocrystalline anisotropy energy of FePt and CoPt ordered alloys. J. Phys. Soc. Jpn 63, 3053–3058 (1994).

    CAS  Article  Google Scholar 

  19. Barman, A. et al. Ultrafast magnetization dynamics in high perpendicular anisotropy [Co/Pt]n multilayers. J. Appl. Phys. 101, 09D102 (2007).

    Article  Google Scholar 

  20. Mizukami, S., Ando, Y. & Miyazaki, T. The study on ferromagnetic resonance linewidth for NM/80NiFe/NM (NM=Cu, Ta, Pd and Pt) films. Jpn. J. Appl. Phys. 40, 580–585 (2001).

    CAS  Article  Google Scholar 

  21. Oogane, M. et al. Magnetic damping in ferromagnetic thin films. Jpn. J. Appl. Phys. 45, 3889–3891 (2006).

    CAS  Article  Google Scholar 

  22. Yakata, S. et al. Influence of perpendicular magnetic anisotropy on spin-transfer switching current in CoFeB/MgO/CoFeB magnetic tunnel junctions. J. Appl. Phys. 105, 07D131 (2009).

    Article  Google Scholar 

  23. Hosomi, M. et al. Progress in spin transfer torque MRAM (SpRAM) development. Magnetics Japan 2, 606–614 (2007) [in Japanese].

    CAS  Google Scholar 

  24. Yamane, K. et al. Memory device and memory. US patent 2009/0285017 A1 (2009).

  25. Draaisma, H. H. G., Jonge, W. J. M. & Broeder, F. J. A. Magnetic interface anisotropy in Pd/Co and Pd/Fe multilayer. J. Magn. Magn. Mater. 66, 351–355 (1987).

    CAS  Article  Google Scholar 

  26. Endo, M., Kanai, S., Ikeda, S., Matsukura, F. & Ohno, H. Electric field effects on thickness dependent magnetic anisotropy of sputtered MgO/Co40Fe40B20/Ta structures. Appl. Phys. Lett. 96, 212503 (2010).

    Article  Google Scholar 

  27. Shimabukuro, R., Nakamura, K., Akiyama, T. & Ito, T. Electric field effects on magnetocrystalline anisotropy in ferromagnetic Fe monolayers. Physica E 42, 1014–1017 (2010).

    CAS  Article  Google Scholar 

  28. Monso, S. et al. Crossover from in-plane to perpendicular anisotropy in Pt/CoFe/AlOx sandwiches as a function of Al oxidation: A very accurate control of the oxidation of tunnel barrier. Appl. Phys. Lett. 80, 4157–4159 (2002).

    CAS  Article  Google Scholar 

  29. Manchon, A. et al. Analysis of oxygen induced anisotropy crossover in Pt/Co/MOx trilayers. J. Appl. Phys. 104, 043914 (2008).

    Article  Google Scholar 

  30. Nistor, L. E., Rodmancq, R., Auffret, A. & Dieny, B. Pt/Co/oxide electrodes for perpendicular magnetic tunnel junctions. Appl. Phys. Lett. 94, 012512 (2009).

    Article  Google Scholar 

  31. Karthik, S.V. et al. Transmission electron microscopy investigation of CoFeB/MgO/CoFeB pseudospin valves annealed at different temperatures. J. Appl. Phys. 106, 023920 (2009).

    Article  Google Scholar 

  32. Koch, R. H., Katine, J. A. & Sun, J. Z. Time-resolved reversal of spin-transfer switching in a nanomagnet. Phys. Rev. Lett. 92, 088302 (2004).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank I. Morita, T. Hirata, A. Fukunaga and S. Koike for their technical support as well as M. Shirai for discussion. The work was supported in part by the ‘High-performance low-power consumption spin devices and storage systems’ program under Research and Development for Next-Generation Information Technology of MEXT, by the Japan Society for the Promotion of Science (JSPS) through its ‘Funding program for world-leading innovative R & D on science and technology (FIRST program)’ and the GCOE program at Tohoku University.

Author information

Affiliations

  1. Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

    S. Ikeda, K. Miura, H. Yamamoto, H. D. Gan, F. Matsukura & H. Ohno

  2. Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

    S. Ikeda, K. Miura, H. Yamamoto, K. Mizunuma, M. Endo, S. Kanai, F. Matsukura & H. Ohno

  3. Hitachi Ltd, Advanced Research Laboratory, 1-280 Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan

    K. Miura, H. Yamamoto & J. Hayakawa

Authors
  1. S. Ikeda
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. K. Miura
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. H. Yamamoto
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. K. Mizunuma
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. H. D. Gan
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. M. Endo
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. S. Kanai
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. J. Hayakawa
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. F. Matsukura
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. H. Ohno
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

S.I. and H.O. planned and supervised the study. S.I., F.M. and H.O. wrote the manuscript. K. Mizunuma, K. Miura, H.Y. and H.D.G. prepared samples and fabricated devices. K. Mizunuma, M.E. and S.K. investigated magnetic characteristics. H.Y. measured FMR spectra. K. Miura and H.Y. investigated the electrical properties of MTJ devices. All authors analysed the data, discussed the result and commented on the manuscript.

Corresponding authors

Correspondence to S. Ikeda or H. Ohno.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Ikeda, S., Miura, K., Yamamoto, H. et al. A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction. Nature Mater 9, 721–724 (2010). https://doi.org/10.1038/nmat2804

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2804

Further reading

Search

Advanced 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