  Proximity-effect and resistance magneto-fluctuations measurements in
submicron Nd1.2Ba1.8Cu3Oz (NBCO) nano-loops are reported to investigate
coherent charge transport in the non-superconducting state. We find an
unexpected inhibition of cooper pair transport, and a destruction of the
induced superconductivity, by lowering the temperature from 6K to 250mK. This
effect is accompanied by a significant change in the conductance-voltage
characteristics and in the zero bias conductance response to the magnetic field
pointing to the activation of a strong pair breaking mechanism at lower
temperature. The data are discussed in the framework of mesoscopic effects
specific to superconducting nanostructures, proximity effect and high
temperature superconductivity.
