2×2 structure and charge inhomogeneity at the surface of superconducting BaFe2−xCoxAs2 (x=0–0.32)

Hui Zhang; Jun Dai; Yujing Zhang; Danru Qu; Huiwen Ji; G. Wu; X. F. Wang; X. H. Chen; Bing Wang; Changgan Zeng; Jinlong Yang; J. G. Hou

doi:10.1103/PhysRevB.81.104520

2×2 structure and charge inhomogeneity at the surface of superconducting BaFe2−xCoxAs2 (x=0–0.32)

Hui Zhang, Jun Dai, Yujing Zhang, Danru Qu, Huiwen Ji, G. Wu, X. F. Wang, X. H. Chen, Bing Wang, Changgan Zeng, Jinlong Yang, J. G. Hou

DOI 10.1103/PhysRevB.81.104520 · Physical Review B

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Abstract

The structure and electronic property at the cleaved (001) surfaces of the newly discovered pnictide superconductors BaFe2−xCoxAs2 with x ranging from 0 to 0.32 are systematically investigated by scanning tunneling microscopy. A 2×2 surface structure is revealed to dominate for all the compounds and is identified to be Ba layer with half Ba atoms lifted off by combination with theoretical simulation. Charge inhomogeneity is observed at this 2×2 surface associated with an energy gap of about 30 meV for all the compounds.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
BaFe1.8Co0.2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
BaFe2-xCoxAs2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown