Filamentary superconductivity across the phase diagram of Ba(Fe,Co)$_2$As$_2$

H. Xiao; T. Hu; S. K. He; B. Shen; W. J. Zhang; B. Xu; K. F. He; J. Han; Y. P. Singh; H. H. Wen; X. G. Qiu; C. Panagopoulos; C. C. Almasan

doi:10.1103/physrevb.86.064521

arXiv · 1208.3352

Filamentary superconductivity across the phase diagram of Ba(Fe,Co)$_2$As$_2$

H. Xiao·T. Hu·S. K. He·B. Shen·W. J. Zhang·B. Xu·K. F. He·J. Han·Y. P. Singh·H. H. Wen·X. G. Qiu·C. Panagopoulos·C. C. Almasan

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Abstract

We show magnetotransport results on Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ ($0.0 \leq x \leq 0.13$) single crystals. We identify the low temperature resistance step at 23 K in the parent compound with the onset of filamentary superconductivity (FLSC), which is suppressed by an applied magnetic field in a similar manner to the suppression of bulk superconductivity (SC) in doped samples. FLSC is found to persist across the phase diagram until the long range antiferromagnetic order is completely suppressed. A significant suppression of FLSC occurs for $0.02<x<0.04$, the doping concentration where bulk SC emerges. Based on these results and the recent report of an electronic anisotropy maximum for 0.02 $\leq x \leq$ 0.04 [Science 329, 824 (2010)], we speculate that, besides spin fluctuations, orbital fluctuations may also play an important role in the emergence of SC in iron-based superconductors.

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H. Xiao, T. Hu, S. K. He, B. Shen, W. J. Zhang, B. Xu, K. F. He, J. Han, Y. P. Singh, H. H. Wen, X. G. Qiu, C. Panagopoulos, C. C. Almasan. 2012-08-16. Filamentary superconductivity across the phase diagram of Ba(Fe,Co)$_2$As$_2$. https://doi.org/10.1103/physrevb.86.064521

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