ИСТИНА

In this talk we summarize the pioneer experimental observation of two collective resonant effects realized in two-gap superconductors (SC) and enhanced by the tunneling. We revisit the Leggett plasma mode (caused by small fluctuations of the phase difference between two SC condensates) in (Mg,Al)B2 superconductor firstly observed by Prof. Ya.G. Ponomarev et al. in 2002, and consider the spin exciton (originated from a presence of a spin-resonance peak in the imaginary part of dynamic spin susceptibility) in SC oxypnictides of the 1111 family observed by us since 2017. We compare and discuss the features of the experimental observation of these effects in the Andreev spectra of planar "break-junctions".