Pressure-tuned superconductivity and normal-state behavior in Ba(Fe1-xCox)2As2 near the antiferromagnetic boundary

Authors: W. Liu, Y. F. Wu, X. J. Li, S. L. Bud'ko, P. C. Canfield, C. Panagopoulos, P. G. Li, G. Mu, T. Hu, C. C. Almasan, and H. Xiao

Published in: Phys. Rev. B 97, 144515, 2018.

Superconductivity in iron pnictides is unconventional and pairing may be mediated by magnetic fluctuations in the Fe sublattice. Pressure is a clean method to explore superconductivity in iron based superconductors by tuning the ground state continuously without introducing disorder. Here we present a systematic high pressure transport study in Ba(Fe1-xCox)2As2 single crystals with x=0.057, which is near the antiferromagnetic instability. Resistivity ρ=ρ0+ATn was studied under applied pressure up to 7.90 GPa. The parameter n approaches a minimum value of n1 at a critical pressure Pc=3.65 GPa. Near  Pc, the superconducting transition temperature Tc reaches a maximum value of 25.8 K. In addition, the superconducting diamagnetism at 2 K shows a sudden change around the same critical pressure. These results may be associated with a possible quantum critical point hidden inside the superconducting dome, near optimum Tc.

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