Advertisement

Origin of Interfacial Magnetic Anisotropy in Ta/CoFeB/MgO and Pt/CoFeB/MgO Multilayer Thin Film Stacks

  • Mustafa AkyolEmail author
Letter
  • 252 Downloads

Abstract

Interfacial perpendicular magnetic anisotropy (PMA) in Pt/Co40Fe40B20/MgO and Ta/Co40Fe40B20/MgO multilayer structures has been researched at various CoFeB layer thicknesses. Magneto-optical Kerr effect (MOKE) and vibrating sample magnetometer (VSM) measurements show that while strong PMA is achieved in Ta/Co40Fe40B20/MgO structure for the thickness of Co40Fe40B20 range from 0.5 to 1.0 nm, a very weak PMA is observed in Pt/Co40Fe40B20/MgO film stack for the same Co40Fe40B20 thicknesses. Based on the experimental results, the interfacial anisotropy energy in Ta/Co40Fe40B20/MgO (1.17 erg/cm2) was found to be almost 2.5× larger than that in Pt/Co40Fe40B20/MgO (0.43 erg/cm2). It is accepted that the PMA comes from the seed/ferromagnetic and ferromagnetic/oxide layer interfaces. Thus, the origin of interfacial magnetic anisotropy can be hybridization and/or crystallinity properties at the interfaces in Ta- and Pt-seeded stacks. While the PMA is strong in Pt/Co/MgO structure, it becomes in-plane in Fe-rich Pt/CoFeB/MgO structure. It is deduced that hybridization between 3d-5d (Co-Pt) orbitals is more dominant in Pt/CoFeB interface than 2p-3d (O-Fe) hybridization at CoFeB/MgO interface in Pt-seeded stacks. In addition, the crystallinity was studied by performing high-resolution x-ray diffraction (HR-XRD) technique. The crystal orientations of Ta and Pt are found as (002) and (111), respectively. The ferromagnetic layer might be induced out-of-plane orientation in Ta-seeded stack due to observing highly crystallized MgO (001). Thus, another reason for in-plane magnetic anisotropy in Pt/Co40Fe40B20/MgO might be the absence of MgO crystallization because Pt is crystallized fcc (111) orientation.

Keywords

PMA Thin films Magnetic multilayer stacks Spintronics 

Notes

Acknowledgments

This work was also partially supported by Çukurova University (Adana/Turkey) and University of California Los Angeles (Los Angeles/USA) in terms of usage of facilities in Device Research Laboratory and Central Research Laboratory. The author thanks Dr. Kang L. Wang, Dr. Pedram K. Amiri, and Dr. Ahmet Ekicibil for their valuable discussion.

Funding Information

This work was partially supported by Adana Science and Technology University (Adana/Turkey) under the project number of 17103024.

References

  1. 1.
    Iwasaki, S.: Perpendicular magnetic recording. IEEE Transactions on Magnetics 16, 71–76 (1980).  https://doi.org/10.1109/TMAG.1980.1060546 ADSCrossRefGoogle Scholar
  2. 2.
    Moodera, J.S., Kinder, L.R., Wong, T.M., Meservey, R.: Large Magnetoresistance at room temperature in ferromagnetic thin film tunnel junctions. Phys. Rev. Lett. 74, 3273–3276 (1995)ADSCrossRefGoogle Scholar
  3. 3.
    Grundy, P.J.: Thin film magnetic recording media. J. Phys. D. Appl. Phys. 31, 2975–2990 (1998)ADSCrossRefGoogle Scholar
  4. 4.
    Parkin, S., Xin, J., Kaiser, C., Panchula, A., Roche, K., Samant, M.: Magnetically engineered spintronic sensors and memory. Proc. IEEE. 91, 661–680 (2003).  https://doi.org/10.1109/JPROC.2003.811807 CrossRefGoogle Scholar
  5. 5.
    Mathon, J., Umerski, A.: Theory of tunneling magnetoresistance of an epitaxial Fe/MgO/Fe(001) junction. Phys. Rev. B. 63, 220403 (2001)ADSCrossRefGoogle Scholar
  6. 6.
    Nishimura, N., Hirai, T., Koganei, A., Ikeda, T., Okano, K., Sekiguchi, Y., Osada, Y.: Magnetic tunnel junction device with perpendicular magnetization films for high-density magnetic random access memory. J. Appl. Phys. 91, 5246–5249 (2002).  https://doi.org/10.1063/1.1459605 ADSCrossRefGoogle Scholar
  7. 7.
    Parkin, S.S.P., Kaiser, C., Panchula, A., Rice, P.M., Hughes, B., Samant, M., Yang, S.H.: Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers. Nat. Mater. 3, 862–867 (2004)ADSCrossRefGoogle Scholar
  8. 8.
    Djayaprawira, D.D., Tsunekawa, K., Nagai, M., et al.: 230% room-temperature magnetoresistance in CoFeB∕MgO∕CoFeB magnetic tunnel junctions. Appl. Phys. Lett. 86, 092502 (2005).  https://doi.org/10.1063/1.1871344 ADSCrossRefGoogle Scholar
  9. 9.
    Wang, K.L., Alzate, J.G., Khalili Amiri, P.: Low-power non-volatile spintronic memory: STT-RAM and beyond. J. Phys. D. Appl. Phys. 46, 074003 (2013).  https://doi.org/10.1088/0022-3727/46/7/074003 ADSCrossRefGoogle Scholar
  10. 10.
    Chiba, D., Yamanouchi, M., Matsukura, F., Ohno, H.: Electrical manipulation of magnetization reversal in a ferromagnetic semiconductor. Science. 301, 943–945 (2003).  https://doi.org/10.1126/science.1086608 ADSCrossRefGoogle Scholar
  11. 11.
    Weisheit, M., Fähler, S., Marty, A., Souche, Y., Poinsignon, C., Givord, D.: Electric field-induced modification of magnetism in thin-film ferromagnets. Science. 315, 349–351 (2007).  https://doi.org/10.1126/science.1136629 ADSCrossRefGoogle Scholar
  12. 12.
    G, Y., Upadhyaya, P., Fan, Y., et al.: Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields. Nat. Nanotechnol. 9, 548–554 (2014).  https://doi.org/10.1038/nnano.2014.94 http://www.nature.com/nnano/journal/v9/n7/abs/nnano.2014.94.html#supplementary-information ADSCrossRefGoogle Scholar
  13. 13.
    Kaidatzis, A., Bran, C., Psycharis, V., Vázquez, M., García-Martín, J.M., Niarchos, D.: Tailoring the magnetic anisotropy of CoFeB/MgO stacks onto W with a Ta buffer layer. Appl. Phys. Lett. 106, 262401 (2015).  https://doi.org/10.1063/1.4923272 ADSCrossRefGoogle Scholar
  14. 14.
    Liu, T., Cai, J.W., Sun, L.: Large enhanced perpendicular magnetic anisotropy in CoFeB/MgO system with the typical Ta buffer replaced by an Hf layer. AIP Adv. 2, 032151 (2012).  https://doi.org/10.1063/1.4748337 ADSCrossRefGoogle Scholar
  15. 15.
    Peng, S., Wang, M., Yang, H., Zeng, L., Nan, J., Zhou, J., Zhang, Y., Hallal, A., Chshiev, M., Wang, K.L., Zhang, Q., Zhao, W.: Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures. Sci. Rep. 5, 18173 (2015).  https://doi.org/10.1038/srep18173 http://www.nature.com/articles/srep18173#supplementary-information ADSCrossRefGoogle Scholar
  16. 16.
    Liu, T., Zhang, Y., Cai, J.W., Pan, H.Y.: Thermally robust Mo/CoFeB/MgO trilayers with strong perpendicular magnetic anisotropy. Sci. Rep. 4, 5895 (2014).  https://doi.org/10.1038/srep05895 ADSCrossRefGoogle Scholar
  17. 17.
    Gweon, H.K., Yun, S.J., Lim, S.H.: A very large perpendicular magnetic anisotropy in Pt/Co/MgO trilayers fabricated by controlling the MgO sputtering power and its thickness. Sci. Rep. 8, 1266 (2018).  https://doi.org/10.1038/s41598-018-19656-9 ADSCrossRefGoogle Scholar
  18. 18.
    Tudu, B., Tian, K., Tiwari, A.: Effect of composition and thickness on the perpendicular magnetic anisotropy of (Co/Pd) multilayers. Sensors (Basel). 17, (2017).  https://doi.org/10.3390/s17122743 CrossRefGoogle Scholar
  19. 19.
    Peng, S., Zhao, W., Qiao, J., Su, L., Zhou, J., Yang, H., Zhang, Q., Zhang, Y., Grezes, C., Amiri, P.K., Wang, K.L.: Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping layer structures. Appl. Phys. Lett. 110, 072403 (2017).  https://doi.org/10.1063/1.4976517 ADSCrossRefGoogle Scholar
  20. 20.
    Cui, B., Song, C., Wang, G.Y., Wang, Y.Y., Zeng, F., Pan, F.: Perpendicular magnetic anisotropy in CoFeB/X (X=MgO, Ta, W, Ti, and Pt) multilayers. J. Alloys Compd. 559, 112–115 (2013).  https://doi.org/10.1016/j.jallcom.2013.01.093 CrossRefGoogle Scholar
  21. 21.
    Akyol, M., Yu, G., Alzate, J.G., et al.: Current-induced spin-orbit torque switching of perpendicularly magnetized Hf|CoFeB|MgO and Hf|CoFeB|TaOxstructures. Appl. Phys. Lett. 106, 162409 (2015).  https://doi.org/10.1063/1.4919108 ADSCrossRefGoogle Scholar
  22. 22.
    Akyol, M., W Jiang, G.Y., et al.: Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures. Appl. Phys. Lett. 109, 022403 (2016).  https://doi.org/10.1063/1.4958295 ADSCrossRefGoogle Scholar
  23. 23.
    Li, M., Lu, J., Akyol, M., et al.: The impact of Hf layer thickness on the perpendicular magnetic anisotropy in Hf/CoFeB/MgO/Ta films. J. Alloys Compd. 694, 76–81 (2017).  https://doi.org/10.1016/j.jallcom.2016.09.309 CrossRefGoogle Scholar
  24. 24.
    Ikeda, S., Miura, K., Yamamoto, H., Mizunuma, K., Gan, H.D., Endo, M., Kanai, S., Hayakawa, J., Matsukura, F., Ohno, H.: A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction. Nat. Mater. 9, 721–724 (2010)ADSCrossRefGoogle Scholar
  25. 25.
    Worledge, D.C., Hu, G., Abraham, D.W., et al.: Spin torque switching of perpendicular Ta∣CoFeB∣MgO-based magnetic tunnel junctions. Appl. Phys. Lett. 98, 022501 (2011).  https://doi.org/10.1063/1.3536482 ADSCrossRefGoogle Scholar
  26. 26.
    Lee, S.-C., Kim, K.-S., Lee, S.-H., et al.: Effect of Fe–O distance on magnetocrystalline anisotropy energy at the Fe/MgO(001) interface. J. Appl. Phys. 113, 023914 (2013).  https://doi.org/10.1063/1.4775604 ADSCrossRefGoogle Scholar
  27. 27.
    Yang, H.X., Chshiev, M., Dieny, B., Lee, J.H., Manchon, A., KH, S.: First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces. Phys. Rev. B. 84, 054401 (2011)ADSCrossRefGoogle Scholar
  28. 28.
    Odkhuu, D., Yun, W.S., Rhim, S.H., Hong, S.C.: Theory of perpendicular magnetocrystalline anisotropy in Fe/MgO (001). J. Magn. Magn. Mater. 414, 126–131 (2016).  https://doi.org/10.1016/j.jmmm.2016.04.027 ADSCrossRefGoogle Scholar
  29. 29.
    Sanghoon, K., Seung-heon Chris, B., Mio, I., et al.: Contributions of Co and Fe orbitals to perpendicular magnetic anisotropy of MgO/CoFeB bilayers with Ta, W, IrMn, and Ti underlayers. Appl. Phys. Express. 10, 073006 (2017).  https://doi.org/10.7567/APEX.10.073006 ADSCrossRefGoogle Scholar
  30. 30.
    Baumann, S., Donati, F., Stepanow, S., et al.: Origin of perpendicular magnetic anisotropy and large orbital moment in Fe atoms on MgO. Phys. Rev. Lett. 115, 237202 (2015).  https://doi.org/10.1103/PhysRevLett.115.237202 ADSCrossRefGoogle Scholar
  31. 31.
    Okabayashi, J., Koo, J.W., Sukegawa, H., Mitani, S., Takagi, Y., Yokoyama, T.: Perpendicular magnetic anisotropy at the interface between ultrathin Fe film and MgO studied by angular-dependent x-ray magnetic circular dichroism. Appl. Phys. Lett. 105, 122408 (2014).  https://doi.org/10.1063/1.4896290 ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Materials EngineeringAdana Science and Technology UniversityAdanaTurkey

Personalised recommendations