Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe2As2 Superconductors

Qiang Zou, Zhiming Wu, Mingming Fu, Chunmiao Zhang, S. Rajput, Yaping Wu, Li Li, D. S. Parker, Junyong Kang, A. S. Sefat, Zheng Gai

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Combined scanning tunneling microscopy, spectroscopy, and local barrier height (LBH) studies show that low-temperature-cleaved optimally doped Ba(Fe1-xCox)2As2 crystals with x = 0.06, with Tc = 22 K, have complicated morphologies. Although the cleavage surface and hence the morphologies are variable, the superconducting gap maps show the same gap widths and nanometer size inhomogeneities irrelevant to the morphology. Based on the spectroscopy and LBH maps, the bright patches and dark stripes in the morphologies are identified as Ba- and As-dominated surface terminations, respectively. Magnetic impurities, possibly due to Co or Fe atoms, are believed to create local in-gap state and, in addition, suppress the superconducting coherence peaks. This study will clarify the confusion on the cleavage surface terminations of the Fe-based superconductors and its relation with the electronic structures.

Original languageEnglish
Pages (from-to)1642-1647
Number of pages6
JournalNano Letters
Volume17
Issue number3
DOIs
StatePublished - Mar 8 2017

Funding

The research is equally supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), the Center for Nanophase Materials Sciences, and Materials Science and Engineering Division (MSD). STM/S experiments were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. Z.W. team’s work was supported by the National Key Research and Development Program of China (No. 2016YFB0400801) and the National Natural Science Foundations of China (No. 61227009).

Keywords

  • Iron-based superconductor
  • STM/S
  • inhomogeneity
  • local barrier height
  • magnetic impurity

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