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We present study of derivatives of current-voltage I(V) characteristics ofpoint-contacts (PCs) based on Ba{1-x}Na{x}Fe2As2 (x=0.25) in the normal andsuperconducting state. The detailed analysis of dV/dI(V) data (also given inAppendix A) shows that the thermal regime, when temperature increases with avoltage at a rate of about 1.8 K/mV, is realized in the investigated PCs atleast at high biases V above the superconducting (SC) gap \Delta. In this case,specific resistivity \rho (T) in PC core is responsible for a peculiar dV/dI(V)behavior, while a pronounced asymmetry of dV/dI(V) is caused by large value ofthermopower in this material. A reproducible zero-bias minima detected ondV/dI(V) at low biases in the range \pm(6--9)mV well below the SC criticaltemperature T_c could be connected with the manifestation of the SC gap \Delta.Evaluation of these Andreev-reflection-like structures on dV/dI(V) points outto the preferred value of 2\Delta/kT_c \approx 6. The expected second gapfeatures on dV/dI(V) are hard to resolve unambiguously, likely due to impurityscattering, spatial inhomogeneity and transition to the mentioned thermalregime as the bias further increases. Suggestions are made how to separatespectroscopic features in dV/dI(V) from those caused by the thermal regime.

Exploring of point-contact spectra of Ba1-xNaxFe2As2 in the normal and superconducting state