We studied SNS- and S-N-S-N-...-S contacts (where S - superconductor, N - normal metal) formed by break-junction technique in polycrystalline Sm$_{1-x}$Th$_x$OFeAs superconductor samples with critical temperatures $T_C = (34 div 45)$ K. In such conta
cts (intrinsic) multiple Andreev reflections effects were observed. Using spectroscopies based on these effects, we detected two independent bulk order parameters and determined their magnitudes. Theoretical analysis of the large and the small gap temperature dependences revealed superconducting properties of Sm$_{1-x}$Th$_x$OFeAs to be driven by intraband coupling, and $sqrt{V_{11}V_{22}}/V_{12} approx 14$ (where $V_{ij}$ - electron-boson interaction matrix elements), whereas the ratio between density of states for the bands with the small and the large gap, $N_2/N_1$, correspondingly, was roughly of an order. We estimated solo BCS-ratio values in a hypothetic case of zero interband coupling ($V_{i e j} = 0$) for each condensate as $2Delta_{L,S}/k_BT_C^{L,S} le 4.5$. The values are constant within the range of critical temperatures studied, and correspond to a case of strong intraband electron-phonon coupling.
Detailed temperature dependence of both superconducting gaps was obtained directly by means of SnS-Andreev spectroscopy. The Delta sigma,pi(T) -curves were shown to be deviated from standard BCS-like behavior, due to k-space proximity effect between
sigma - and pi - condensates, which could give a key to experimental determination of interband electron-phonon coupling constants. For the first time, an excellent qualitative agreement with theoretical predictions of Nicol and Carbotte, and Moskalenko and Suhl was shown. dI(V)/dV-spectra of SnS-Andreev contacts based on MgB2 samples (with defects of crystal structure), and Mg(Al)B2 polycrystalline samples (with the local critical temperatures Tc variation 10 K < Tc < 37 K) were studied by means of the break-junction technique within the temperature range 4.2 K < T < Tc.
