Metal-insulator transition at a surface of a ferromagnetic-metal La$_{0.75}$Ca$_{0.25}$MnO$_3$/SrTiO$_3$(100) thin film

ORAL

Abstract

We have performed low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) measurements on a ferromagnetic-metal La$_{0.75}$Ca$_{0.25}$MnO$_3$/SrTiO$_3$(100) thin film surface. Our topographic images show two-domain zigzag patterns with ($\sqrt{2}\times\sqrt{2}$) periodicities in the perovskite structure. In addition, we measured an energy gap at the Fermi level in our STS spectra, in contrast to the ferromagnetic-metal properties obtained by ensemble measurements. First-principle calculations suggest that the topmost zigzag structure is caused by the structural relaxation based on the orthorhombic nature in bulk, suppressing the carrier itinerancy.

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Authors

  • Ryota Shimizu

    • AIMR, Tohoku University, Japan
    • AIMR, Tohoku University

  • Shunya Nakamura

    • Department of Materials Engineering, The University of Tokyo

  • Yasunobu Ando

    • Department of Materials Engineering, The University of Tokyo

  • Emi Minamitani

    • Department of Materials Engineering, The University of Tokyo

  • Katsuya Iwaya

    • RIKEN, AIMR in Tohoku University

  • Takeo Ohsawa

    • NIMS, AIMR in Tohoku University

  • Satoshi Watanabe

    • Department of Materials Engineering, The University of Tokyo

  • Taro Hitosugi

    • AIMR, Tohoku University, JST-PRESTO