Abstract

There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin–orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin–orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions.

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Acknowledgements

We thank H. Y. Hwang and J. S. Lee for discussion, and Y. Ishida for his help in the ARPES experiment. This research is supported by the Japan Society for the Promotion of Science through the ‘Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program)’, initiated by the Council for Science and Technology Policy.

Author information

Affiliations

  1. Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan

    • K. Ishizaka
    • , M. Sakano
    • , T. Shimojima
    • , T. Sonobe
    • , R. Arita
    • , N. Nagaosa
    • , Y. Onose
    •  & Y. Tokura
  2. Correlated Electron Research Group (CERG), RIKEN-ASI, Wako 351-0918, Japan

    • M. S. Bahramy
    • , R. Arita
    • , N. Nagaosa
    •  & Y. Tokura
  3. Multiferroics Project, ERATO, JST, Tokyo 113-8656, Japan

    • H. Murakawa
    • , Y. Kaneko
    • , Y. Onose
    •  & Y. Tokura
  4. Institute for Solid State Physics, University of Tokyo, Kashiwa, 277-8581, Japan

    • K. Koizumi
    •  & S. Shin
  5. CREST, JST, Tokyo 102-0075, Japan

    • S. Shin
  6. Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan

    • H. Miyahara
    • , A. Kimura
    •  & M. Taniguchi
  7. Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan

    • K. Miyamoto
    • , T. Okuda
    • , H. Namatame
    •  & M. Taniguchi
  8. Condensed Matter Research Center, Institute of Materials Structure Science, KEK, Tsukuba, 305-0801, Japan

    • K. Kobayashi
    • , Y. Murakami
    •  & R. Kumai
  9. National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan

    • R. Kumai

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Contributions

K.I., M.S., T. Shimojima and T. Sonobe carried out (SR)ARPES. K. Koizumi and S.S. shared the ARPES infrastructure at the Institute of Solid State Physics and assisted with measurements. H.M., A.K., K.M., T.O., H.N. and M.T. shared the SRARPES infrastructure at the Hiroshima Synchrotron Radiation Center and assisted with measurements. M.S.B., R.A. and N.N. carried out the calculations. K. Kobayashi, Y.M. and R.K. carried out X-ray diffraction and determined the crystal structure. H.M., Y.K. and Y.O. carried out the crystal growth and transport measurements. K.I. analysed the (SR)ARPES data and wrote the manuscript with input from M.S.B., H.M., R.A., N.N. and Y.T. Y.T. conceived and coordinated the project.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to K. Ishizaka.

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DOI

https://doi.org/10.1038/nmat3051