Giant Rashba-type spin splitting in bulk BiTeI

Journal name:
Nature Materials
Volume:
10,
Pages:
521–526
Year published:
DOI:
doi:10.1038/nmat3051
Received
Accepted
Published online

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.

At a glance

Figures

  1. Basic properties of BiTeI.
    Figure 1: Basic properties of BiTeI.

    a, Crystal structure. b, Brillouin zone. c, Temperature-dependent electrical resistivity. d, Energy-band dispersions obtained by relativistic first-principles band calculation.

  2. Rashba-split conduction bands observed by ARPES (hν=21.2 eV).
    Figure 2: Rashba-split conduction bands observed by ARPES (hν=21.2 eV).

    a, Fermi-surface mapping overlaid on the two-dimensional Brillouin zone of BiTeI. b, Angle-integrated PES around the kII=0 region. The near- EF part is magnified (×30) to show the conduction-band structure. c, The ARPES image of the Rashba-split conduction bands. The right panels show the band contour images as functions of kx and ky at certain binding energies.

  3. Spin polarization of Rashba-split bands.
    Figure 3: Spin polarization of Rashba-split bands.

    a, Markers tracking the band dispersions overlaid on the ARPES intensity image. The markers show the peak positions of the EDCs and MDCs. Red (blue) markers represent the ‘spin-up’ ( ‘spin-down’) components, as confirmed by SRARPES shown in c,d. b, The Fermi-surface map. Green markers show the peak positions of MDCs at EF. The red line represents the momentum cut of the SRARPES images in c,d. c, The spin-polarization image obtained by SRARPES. d, The EDCs of SRARPES measured along kx . The red (blue) curves show the spin-up (spin-down) components. e, Calculated spin polarization on conduction-band dispersions along A–L (ky=0,kz=π/c). Only the -component is shown by the colour scale for comparison with the experiment. f, Calculated spin polarization overlaid on the Fermi surface at kz=π/c. The arrows show the orientation of spin whereas their colour indicates the degree of polarization.

  4. Subband structure of Rashba-split conduction band quantized in the band-bending accumulation layer.
    Figure 4: Subband structure of Rashba-split conduction band quantized in the band-bending accumulation layer.

    a, ARPES image along kx obtained by an hν=6.994 eV laser light source. The red markers show the peak positions of the EDC and MDC. The blue (green) curve is a guide for the eyes to trace the dispersions of the n=1 (n=2) subband. b, Calculated subband structures taking into account the quantization of the conduction band in the two-dimensional surface accumulation layer. c, The calculated potential energy as a function of the depth from the surface (z). d, The calculated electron density as a function of z.

References

  1. Rashba, E. I. Properties of semiconductors with an extremum loop. 1. Cyclotron and combinational resonance in a magnetic field perpendicular to the plane of the loop. Sov. Phys. Solid State 2, 11091122 (1960).
  2. Casella, R. C. Toroidal energy surfaces in crystals with wurtzite symmetry. Phys. Rev. Lett. 5, 371373 (1960).
  3. Bychkov, Y. A. & Rashba, E. I. Properties of a 2D electron gas with lifted spectral degeneracy. JETP Lett. 39, 7881 (1984).
  4. Nitta, J., Akazaki, T., Takayanagi, H. & Enoki, T. Gate control of spin–orbit interaction in an inverted In0.53Ga0.47As/In0.52Al0.48As heterostructure. Phys. Rev. Lett. 78, 13351338 (1997).
  5. LaShell, S., McDougall, B. A. & Jensen, E. Spin splitting of Au(111) surface state band observed with angle resolved photoelectron spectroscopy. Phys. Rev. Lett. 77, 34193422 (1996).
  6. Hoesch, M. et al. Spin structure of the Shockley surface state on Au(111). Phys. Rev. B 69, 241401 (2004).
  7. Ast, C. R. et al. Giant spin splitting through surface alloying. Phys. Rev. Lett. 98, 186807 (2007).
  8. Gierz, I. et al. Silicon surface with giant spin splitting. Phys. Rev. Lett. 103, 046803 (2009).
  9. Datta, S. & Das, B. Electronic analog of the electro-optic modulator. Appl. Phys. Lett. 56, 665667 (1990).
  10. Sinova, J. et al. Universal intrinsic spin Hall effect. Phys. Rev. Lett. 92, 126603 (2004).
  11. Bauer, E. et al. Heavy fermion superconductivity and magnetic order in noncentrosymmetric CePt3Si. Phys. Rev. Lett. 92, 027003 (2004).
  12. Shevelkov, A. V., Dikarev, E. V., Shpanchenko, R. V. & Popovkin, B. A. Crystal structures of bismuth tellurohalides BiTeX (X=Cl, Br, I) from X-ray powder diffraction data. J. Solid State Chem. 114, 379384 (1995).
  13. Hashimoto, S. et al. The de Haas-van Alphen effect and the Fermi surface in CePt3Si and LaPt3Si. J. Phys. Condens. Matter 16, L287L296 (2004).
  14. Lee, K. W. & Pickett, W. E. Crystal symmetry, electron–phonon coupling, and superconducting tendencies in Li2Pd3B and Li2Pt3B. Phys. Rev. B 72, 174505 (2005).
  15. Tomokiyo, A., Okada, T. & Kawano, S. Phase diagram of system (Bi2Te3)–(BiI3) and crystal structure of BiTeI. Jpn. J. Appl. Phys. 16, 291298 (1977).
  16. Koroteev, Y. M. et al. Strong spin–orbit splitting on Bi surfaces. Phys. Rev. Lett. 93, 046403 (2004).
  17. Kimura, A. et al. Strong Rashba-type spin polarization of the photocurrent from bulk continuum states: Experiment and theory for Bi(111). Phys. Rev. Lett. 105, 076804 (2010).
  18. Hirahara, T. et al. Role of spin–orbit coupling and hybridization effects in the electronic structure of ultrathin Bi films. Phys. Rev. Lett. 97, 146803 (2006).
  19. Hirahara, T. et al. Direct observation of spin splitting in bismuth surface states. Phys. Rev. B 76, 153305 (2007).
  20. Mathias, S. et al. Quantum-well induced giant spin–orbit splitting. Phys. Rev. Lett. 104, 066802 (2010).
  21. Lo, I. et al. Anomalous k-dependent spin splitting in wurtzite AlxGa1−xN/GaN heterostructures. Phys. Rev. B 75, 245307 (2007).
  22. Wang, W. T. et al. Dresselhaus effect in bulk wurtzite materials. Appl. Phys. Lett. 91, 082110 (2007).
  23. Cartoixà, X., Ting, D. Z-Y. & Chang, Y-C. Suppression of the D’yakonov-Perel’ spin-relaxation mechanism for all spin components in [111] zincblende quantum wells. Phys. Rev. B 71, 045313 (2005).
  24. Seah, M. P. & Dench, W. A. Quantitative electron spectroscopy of surfaces: A standard data base for electron inelastic mean free paths in solids. Surf. Interface Anal. 1, 211 (1979).
  25. Takeda, S. N., Higashi, N. & Daimon, H. Visualization of in-plane dispersion of hole subbands by photoelectron spectroscopy. Phys. Rev. Lett. 94, 037401 (2005).
  26. King, P. D. C. et al. Surface band-gap narrowing in quantized electron accumulation layers. Phys. Rev. Lett. 104, 256803 (2010).
  27. King, P. D. C., Veal, T. D. & McConville, C. F. Nonparabolic coupled Poisson–Schrödinger solutions for quantized electron accumulation layers: Band bending, charge profile, and subbands in InN surfaces. Phys Rev. B 77, 125305 (2008).
  28. Edelstein, V. M. Spin polarization of conduction electrons induced by electric current in two-dimensional asymmetric electron systems. Solid State Commun. 73, 233235 (1990).
  29. Miron, I. M. et al. Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer. Nature Mater. 9, 230234 (2010).
  30. Kiss, T. et al. A versatile system for ultrahigh resolution, low temperature, and polarization dependent laser-angle-resolved photoemission spectroscopy. Rev. Sci. Instrum. 79, 023106 (2008).
  31. Iori, K. et al. The self-calibration of a retarding-type Mott spin polarimeter with a large collection angle. Rev. Sci. Instrum. 77, 013101 (2006).
  32. Blaha, P., Shwarz, K., Madsen, G., Kvasnicka, D. & Luiz, J. WIEN2K package; available at, http://www.wien2k.at.
  33. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 38653868 (1996).
  34. Mostofi, A. A., Yates, J. R., Lee, Y-S., Vanderbilt, D. & Marzari, N. Wannier90: A tool for obtaining maximally localized Wannier functions. Comp. Phys. Commun. 178, 685699 (2008).
  35. Kuneš, J. et al. WIEN2WANNIER: From linearized augmented plane waves to maximally localized Wannier functions. Comp. Phys. Commun. 181, 18881895 (2010).
  36. Dil, J. H. et al. Rashba-type spin–orbit splitting of quantum well states in ultrathin Pb films. Phys. Rev. Lett. 101, 266802 (2008).
  37. Hirahara, T. et al. Quantum well states in ultrathin Bi films: Angle-resolved photoemission spectroscopy and first-principles calculations study. Phys. Rev. B 75, 035422 (2007).

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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

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.

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The authors declare no competing financial interests.

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