Observation of subgap resistive oscillations in doubly connected $SNS$ systems with the suppressed proximity effect

Phase-sensitive magnetoresistive oscillations were observed at temperatures $T<4\,$ K in hybrid quasi ballistic doubly connected $SNS$ structures with single-crystal normal spacers of macroscopic sizes in all dimensions ($L=100\div500 \mu m$) and elastic electron mean free path on the same scale $l_{el}\sim100\mu m$. The oscillations observed for the distances corresponding to the indicated $L$ values between the $NS$ interfaces are evidence that the phase-interruption length in pure metal is macroscopic at $T<4\,$ K. The oscillation parameters related to the geometry of structures and spacer sizes indicate the quantum nature of the oscillations. These are shown to reflect the behavior of conductance in the $NS$ interfaces with the dissipative coherent transport of «subgap» quasiparticles with energies $\varepsilon \ll \Delta, T (\Delta$ is the gap energy).