LEED pattern of clean STO substrate at 70 eV

Surface reconstruction and charge modulation in BaFe2As2 superconducting film

JUNE, 2018

Sungmin Kim, Sun Ouk Yi, Myungchul Oh, Bo Gyu Jang, W Nam, Yong-Chan Yoo, Minjun Lee, Hoyean Jeon, Inhae Zoh, Hanho Lee, Chao Zhang, Kee Hoon Kim, JungPil Seo, Ji Hoon Shim, Jungseok Chae, Young Kuk
Journal of Physics: Condensed Matter 30, 315001 (2018)


Whether or not epitaxially grown superconducting films have the same bulk-like superconducting properties is an important concern. We report the structure and the electronic properties of epitaxially grown Ba(Fe1−x Cox )2As2 films using scanning tunneling microscopy and scanning tunneling spectroscopy (STS). This film showed a different surface structure, (2 √ 2 x 2 √ 2) R45° reconstruction, from those of as-cleaved surfaces from bulk crystals. The electronic structure of the grown film is different from that in bulk, and it is notable that the film exhibits the same superconducting transport properties. We found that the superconducting gap at the surface is screened at the Ba layer surface in STS measurements, and the charge density wave was observed at the surface in sample in the superconducting state.