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arXiv · 1301.3719

Point-contact spectroscopy in Co-doped CaFe2As2: nodal superconductivity and topological Fermi surface transition

R. S. Gonnelli·M. Tortello·D. Daghero·R. K. Kremer·Z. Bukowski·N. D. Zhigadlo·J. Karpinski
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Abstract

We performed point-contact Andreev reflection spectroscopy measurements in Ca(Fe_{1-x}Co_x)2As2 single crystals with effective x=0.060 +- 0.005. The spectra of ab-plane contacts show a zero-bias maximum and broad shoulders at about 5-6 meV. Their fit with the three-dimensional Blonder-Tinkham-Klapwijk model (making use of a analytical expression for the Fermi surface that mimics the one calculated from first principles) shows that this compound presents a large isotropic gap on the quasi-2D electronlike Fermi surface sheets and a smaller anisotropic (possibly nodal) gap on the 3D holelike Fermi surface pockets centered at the Z point in the Brillouin zone. These results nicely fit into the theoretical picture for the appearance of nodal superconductivity in 122 compounds.

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R. S. Gonnelli, M. Tortello, D. Daghero, R. K. Kremer, Z. Bukowski, N. D. Zhigadlo, J. Karpinski. 2013-01-16. Point-contact spectroscopy in Co-doped CaFe2As2: nodal superconductivity and topological Fermi surface transition. https://doi.org/10.1088/0953-2048%2F25%2F6%2F065007

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