Scanning Tunneling Spectroscopy and Vortex Imaging in the Iron-Pnictide Superconductor BaFe$_{1.8}$Co$_{0.2}$As$_2$
| Autor: | Yin, Yi, Zech, M., Williams, T. L., Wang, X. F., Wu, G., Chen, X. H., Hoffman, J. E. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 102, 097002 (2009) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.102.097002 |
| Popis: | We present an atomic resolution scanning tunneling spectroscopy study of superconducting BaFe$_{1.8}$Co$_{0.2}$As$_2$ single crystals in magnetic fields up to $9 \text{Tesla}$. At zero field, a single gap with coherence peaks at $\overline{\Delta}=6.25 \text{meV}$ is observed in the density of states. At $9 \text{T}$ and $6 \text{T}$, we image a disordered vortex lattice, consistent with isotropic, single flux quantum vortices. Vortex locations are uncorrelated with strong scattering surface impurities, demonstrating bulk pinning. The vortex-induced sub-gap density of states fits an exponential decay from the vortex center, from which we extract a coherence length $\xi=27.6\pm 2.9 \text{\AA}$, corresponding to an upper critical field $H_{c2}=43 \text{T}$. Comment: 4 pages, 4 figures |
| Databáze: | arXiv |
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