title: Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe2As2Superconductors.
abstract: Combined scanning tunneling microscopy, spectroscopy, and local barrier height (LBH) studies show that low-temperature-cleaved optimally doped Ba(Fe1-xCox)2As2crystals 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.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zou
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University , Xiamen, Fujian Province 361005, P. R. China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University , Xiamen, Fujian Province 361005, P. R. China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Fu
authors.affiliation: Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University , Xiamen, Fujian Province 361005, P. R. China.
authors.forename: Chunmiao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: S
authors.initials: S
authors.lastname: Rajput
authors.affiliation: Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University , Xiamen, Fujian Province 361005, P. R. China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: D S
authors.initials: DS
authors.lastname: Parker
authors.affiliation: Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics, Xiamen University , Xiamen, Fujian Province 361005, P. R. China.
authors.forename: Junyong
authors.initials: J
authors.lastname: Kang
authors.affiliation: Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: A S
authors.initials: AS
authors.lastname: Sefat
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Zheng
authors.identifier: 0000-0002-6099-4559
authors.initials: Z
authors.lastname: Gai
keywords: Iron-based superconductor; STM/S; inhomogeneity; local barrier height; magnetic impurity