Temperature-dependent transport characteristics of quasiballistic normal-metal-superconductor junctions

We study the temperature effect on the zero-bias conductance and current fluctuations in a two-terminal heterostructure with a mesoscopic normal region connected to normal and superconducting reservoirs. For a quasiballistic regime, the shape of the conductance-voltage characteristic and its temperature behavior for an s-wave superconductor strongly depends on the transmission properties of the normal interlayer. On the contrary, in the low-frequency limit, the near-zero-voltage current noise power versus temperature is insensitive to the nature of the transition region but dramatically changes for different pairing states of the superconducting electrode. The relevant experiment could serve as a diagnostic tool to identify the symmetry of the superconducting order parameter in high-temperature superconductors.