Extraordinary Temperature Dependence of the Resonant Andreev Reflection

An extraordinary temperature dependence of the resonant Andreev reflection via discrete energy level in a normal-metal / quantum-dot / superconductor (N-QD-S) system is predicted theoretically by using Green function technique. The width of zero bias conductance peak in N-QD-S is about √ ΓL + Γ 2 R and does not exhibit thermal broadening, where ΓL and ΓR are the coupling strength between QD and leads. Considering the intra-dot Coulomb interaction, the Coulomb blockade oscillations conducted by Andreev reflection differs dramatically from that in N-QD-N. Instead of thermal broadening, finite temperature induces more resonant peaks around the oscillation peaks of zero temperature. This effect can be applied to determine the coupling strength and QD level spacing in N-QD-S. PACS numbers: 74.50.+r, 73.40.Gk, 73.20.Dx, 72.15.Nj.