Filamentary superconductivity across the phase diagram of Ba(Fe,Co)2As2

Authors: 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 and C. C. Almasan

Published in: Phys. Rev. B 86, 064521, 2012.

We show magnetotransport results on Ba(Fe1−xCox)2As2 (0.0⩽x⩽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 ⩽x⩽ 0.04 [ Chu et al. 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.

You can read the article here.