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Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO

Nature Materials 12, 240–245 (2013) | Download Citation

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Abstract

Current-induced effective magnetic fields can provide efficient ways of electrically manipulating the magnetization of ultrathin magnetic heterostructures. Two effects, known as the Rashba spin orbit field and the spin Hall spin torque, have been reported to be responsible for the generation of the effective field. However, a quantitative understanding of the effective field, including its direction with respect to the current flow, is lacking. Here we describe vector measurements of the current-induced effective field in Ta|CoFeB|MgO heterostructrures. The effective field exhibits a significant dependence on the Ta and CoFeB layer thicknesses. In particular, a 1 nm thickness variation of the Ta layer can change the magnitude of the effective field by nearly two orders of magnitude. Moreover, its sign changes when the Ta layer thickness is reduced, indicating that there are two competing effects contributing to it. Our results illustrate that the presence of atomically thin metals can profoundly change the landscape for controlling magnetic moments in magnetic heterostructures electrically.

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Acknowledgements

The authors acknowledge helpful discussions with H-W. Lee, K-J. Lee and T. Taniguchi. We thank M. Kodzuka, T. Ohkubo and K. Hono for their support on film characterization. This work was partly supported by the Japan Society for the Promotion of Science (JSPS) though its ‘Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST program)’.

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Affiliations

  1. National Institute for Materials Science, Tsukuba 305-0047, Japan

    • Junyeon Kim
    • , Jaivardhan Sinha
    • , Masamitsu Hayashi
    •  & Seiji Mitani

  2. Center for Spintronics Integrated Systems, Tohoku University, Sendai 980-8577, Japan

    • Michihiko Yamanouchi
    • , Shunsuke Fukami
    •  & Hideo Ohno

  3. Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan

    • Michihiko Yamanouchi
    •  & Hideo Ohno

  4. Renesas Electronics Corporation, Sagamihara 252-5298, Japan

    • Tetsuhiro Suzuki

  5. WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

    • Hideo Ohno

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Contributions

M.H. planned the study. J.K., M.H., M.Y. and H.O. wrote the manuscript. J.S. performed film deposition and film characterization, M.H. fabricated the devices. J.K. carried out the measurements and analysed the data with the help of M.H., M.Y., S.F., T.S., S.M. and H.O. All authors discussed the data and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Masamitsu Hayashi.

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https://doi.org/10.1038/nmat3522