Evidence for two-gap superconductivity in Ba0.55K0.45Fe2As2 from directional point-contact Andreev-reflection spectroscopy
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2009-01-01
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https://doi.org/10.1103/PhysRevB.79.012503
Abstract
Directional point-contact Andreev-reflection spectroscopy measurements on the Ba0.55K0.45Fe2As2 single crystals are presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction of the crystal. In the latter case only a reduced point-contact conductance around zero bias has been revealed persisting well above T-c and probably related to the structural and magnetic transitions in the system. Within the ab plane two superconducting energy gaps are detected below T-c. Here a reduced conductance above T-c could also be found. The fits of the ab-plane data to the superconducting s-wave two-gap model indicate that the smaller gap has a size below the BCS value while the large gap reveals much higher coupling strength.
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This article is published as Szabó, P., Z. Pribulová, G. Pristáš, S. L. Bud’ko, P. C. Canfield, and P. Samuely. "Evidence for two-gap superconductivity in Ba 0.55 K 0.45 Fe 2 As 2 from directional point-contact Andreev-reflection spectroscopy." Physical Review B 79, no. 1 (2009): 012503.
DOI: 10.1103/PhysRevB.79.012503
Copyright 2009 American Physical Society.
Posted with permission.