Electronic structure and polar catastrophe at the surface of Lix CoO2 studied by angle-resolved photoemission spectroscopy

Y. Okamoto, R. Matsumoto, T. Yagihara, C. Iwai, K. Miyoshi, J. Takeuchi, K. Horiba, M. Kobayashi, K. Ono, H. Kumigashira, N. L. Saini, Takashi Mizokawa

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    We report an angle-resolved photoemission spectroscopy (ARPES) study of LixCoO2 single crystals which have a hole-doped CoO2 triangular lattice. Similar to NaxCoO2, the Co 3da1g band crosses the Fermi level with strongly renormalized band dispersion while the Co 3deg′ bands are fully occupied in LixCoO2 (x=0.46 and 0.71). At x=0.46, the Fermi surface area is consistent with the bulk hole concentration indicating that the ARPES result represents the bulk electronic structure. On the other hand, at x=0.71, the Fermi surface area is larger than the expectation which can be associated with the inhomogeneous distribution of Li reported in the previous scanning tunneling microscopy study by Iwaya et al. [Phys. Rev. Lett. 111, 126104 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.126104]. However, the Co 3d peak is systematically shifted towards the Fermi level with hole doping excluding phase separation between hole rich and hole poor regions in the bulk. Therefore, the deviation of the Fermi surface area at x=0.71 can be attributed to hole redistribution at the surface avoiding polar catastrophe. The bulk Fermi surface of Co 3da1g is very robust around x=0.5 even in the topmost CoO2 layer due to the absence of the polar catastrophe.

    Original languageEnglish
    Article number125147
    JournalPhysical Review B
    Volume96
    Issue number12
    DOIs
    Publication statusPublished - 2017 Sep 25

    Fingerprint

    Fermi surface
    Photoelectron spectroscopy
    Electronic structure
    photoelectric emission
    electronic structure
    Fermi surfaces
    Fermi level
    spectroscopy
    Hole concentration
    Scanning tunneling microscopy
    Phase separation
    Doping (additives)
    Single crystals
    scanning tunneling microscopy
    deviation
    single crystals

    ASJC Scopus subject areas

    • Condensed Matter Physics

    Cite this

    Electronic structure and polar catastrophe at the surface of Lix CoO2 studied by angle-resolved photoemission spectroscopy. / Okamoto, Y.; Matsumoto, R.; Yagihara, T.; Iwai, C.; Miyoshi, K.; Takeuchi, J.; Horiba, K.; Kobayashi, M.; Ono, K.; Kumigashira, H.; Saini, N. L.; Mizokawa, Takashi.

    In: Physical Review B, Vol. 96, No. 12, 125147, 25.09.2017.

    Research output: Contribution to journalArticle

    Okamoto, Y, Matsumoto, R, Yagihara, T, Iwai, C, Miyoshi, K, Takeuchi, J, Horiba, K, Kobayashi, M, Ono, K, Kumigashira, H, Saini, NL & Mizokawa, T 2017, 'Electronic structure and polar catastrophe at the surface of Lix CoO2 studied by angle-resolved photoemission spectroscopy', Physical Review B, vol. 96, no. 12, 125147. https://doi.org/10.1103/PhysRevB.96.125147
    Okamoto, Y. ; Matsumoto, R. ; Yagihara, T. ; Iwai, C. ; Miyoshi, K. ; Takeuchi, J. ; Horiba, K. ; Kobayashi, M. ; Ono, K. ; Kumigashira, H. ; Saini, N. L. ; Mizokawa, Takashi. / Electronic structure and polar catastrophe at the surface of Lix CoO2 studied by angle-resolved photoemission spectroscopy. In: Physical Review B. 2017 ; Vol. 96, No. 12.
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    abstract = "We report an angle-resolved photoemission spectroscopy (ARPES) study of LixCoO2 single crystals which have a hole-doped CoO2 triangular lattice. Similar to NaxCoO2, the Co 3da1g band crosses the Fermi level with strongly renormalized band dispersion while the Co 3deg′ bands are fully occupied in LixCoO2 (x=0.46 and 0.71). At x=0.46, the Fermi surface area is consistent with the bulk hole concentration indicating that the ARPES result represents the bulk electronic structure. On the other hand, at x=0.71, the Fermi surface area is larger than the expectation which can be associated with the inhomogeneous distribution of Li reported in the previous scanning tunneling microscopy study by Iwaya et al. [Phys. Rev. Lett. 111, 126104 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.126104]. However, the Co 3d peak is systematically shifted towards the Fermi level with hole doping excluding phase separation between hole rich and hole poor regions in the bulk. Therefore, the deviation of the Fermi surface area at x=0.71 can be attributed to hole redistribution at the surface avoiding polar catastrophe. The bulk Fermi surface of Co 3da1g is very robust around x=0.5 even in the topmost CoO2 layer due to the absence of the polar catastrophe.",
    author = "Y. Okamoto and R. Matsumoto and T. Yagihara and C. Iwai and K. Miyoshi and J. Takeuchi and K. Horiba and M. Kobayashi and K. Ono and H. Kumigashira and Saini, {N. L.} and Takashi Mizokawa",
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    AU - Iwai, C.

    AU - Miyoshi, K.

    AU - Takeuchi, J.

    AU - Horiba, K.

    AU - Kobayashi, M.

    AU - Ono, K.

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    AB - We report an angle-resolved photoemission spectroscopy (ARPES) study of LixCoO2 single crystals which have a hole-doped CoO2 triangular lattice. Similar to NaxCoO2, the Co 3da1g band crosses the Fermi level with strongly renormalized band dispersion while the Co 3deg′ bands are fully occupied in LixCoO2 (x=0.46 and 0.71). At x=0.46, the Fermi surface area is consistent with the bulk hole concentration indicating that the ARPES result represents the bulk electronic structure. On the other hand, at x=0.71, the Fermi surface area is larger than the expectation which can be associated with the inhomogeneous distribution of Li reported in the previous scanning tunneling microscopy study by Iwaya et al. [Phys. Rev. Lett. 111, 126104 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.126104]. However, the Co 3d peak is systematically shifted towards the Fermi level with hole doping excluding phase separation between hole rich and hole poor regions in the bulk. Therefore, the deviation of the Fermi surface area at x=0.71 can be attributed to hole redistribution at the surface avoiding polar catastrophe. The bulk Fermi surface of Co 3da1g is very robust around x=0.5 even in the topmost CoO2 layer due to the absence of the polar catastrophe.

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