Surface effect of epitaxially grown BaFe$_{\mathrm{2}}$As$_{\mathrm{2}}$ surface -- Scanning Tunneling Microscopy and Spectroscopy study

ORAL

Abstract

The electronic properties of Co-doped BaFe$_{\mathrm{2}}$As$_{\mathrm{2}}$ (BFCA) iron pnictide superconductors were studied using scanning tunneling microscopy and spectroscopy. BFCA samples with superconducting transition temperatures 22-27 K, were grown on SrTiO$_{\mathrm{3}}$(100) by pulsed laser deposition (PLD) growth under ultrahigh vacuum condition. As-grown surfaces revealed $2\times 2$or $2\sqrt 2 \times 2\sqrt 2 $structures as a function of bias voltage at 4.3 K. Missing row structures were also observed on as-grown samples, suggesting many nucleation sites and resultant antiphase boundaries. The I-V and dI/dV spectra were deviated from the bulk spectrum obtained by contact conductance measurement. After removing surface layers by ion beam sputtering, different spectra were observed. The obtained spectra were explained with the surface state effect in BFCA samples as compared with DFT calculations.

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Authors

  • Sungmin Kim

    • Department of Physics and Astronomy, Seoul National University

  • Sunwouk Yi

    • Department of Physics and Astronomy, Seoul National University

  • Minjun Lee

    • Department of Physics and Astronomy, Seoul National University

  • Hanho Lee

    • Department of Physics and Astronomy, Seoul National University

  • Hoyeon Jeon

    • Department of Physics and Astronomy, Seoul National University

  • Yongchan Yoo

    • Department of Physics and Astronomy, Seoul National University

  • Inhae Zoh

    • Department of Physics and Astronomy, Seoul National University

  • Chao Zhang

    • Department of Physics and Astronomy, Seoul National University

  • Myungchul Oh

    • Department of Physics and Astronomy, Seoul National University

  • Young Kuk

    • Department of Physics and Astronomy, Seoul National University
    • Department of Physics and Astronomy, Seoul National University, Republic of Korea