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We report on the results of directional point-contact Andreev-reflection(PCAR) measurements in Ba(Fe_{1-x}Co_x)2As2 single crystals and epitaxialc-axis oriented films with x = 0.08 as well as in Ca(Fe_{1-x}Co_x)2As2 singlecrystals with x = 0.06. The PCAR spectra are analyzed within the two-band 3Dversion of the Blonder-Tinkham-Klapwijk model for Andreev reflection werecently developed, and that makes use of an analytical expression for theFermi surface that mimics the one calculated within the density-functionaltheory (DFT). The spectra in Ca(Fe_{0.94}Co_{0.06})2As2 unambiguouslydemonstrate the presence of nodes or zeros in the small gap. InBa(Fe_{0.92}Co_{0.08})2As2, the ab-plane spectra in single crystals can befitted by assuming two nodeless gaps, but this model fails to fit the c-axisones in epitaxial films. All these results are discussed in comparison withrecent theoretical predictions about the occurrence of accidental 3D nodes andthe presence of "hot spots" in the gaps of 122 compounds.

The order-parameter symmetry and Fermi surface topology of 122 Fe-based superconductors: a point-contact Andreev-reflection study