Current-Voltage Characteristics for a Tunnel Junction Composed of a Conductor with a CDW and Superconductor

Abstract

Current-voltage (J-V ) and differential-conductivity-voltage (dJ/dV -V ) characteristics are analytically calculatedat zero temperature for a tunnel junction: a supercond uctor (S) and a Peierls conductor (P) separated by an insulator (I). Here P is a conductor with a charge density wave (CDW). The Hamiltonians of S and P are treated in the mean field approximation. To calculate the current J analytically, ∆S = ∆P ≡ ∆ is assumed, where ∆S and ∆P are the energy gaps of S andP, respectively. When the secondorder of the perturbation theory in the tunnel Hamiltonian is considered in the conventional tunnel Hamiltonian approach, the J-V and dJ/dV -V characteristics depend on only the CDW phase ϕ. The current J has a discontinuous jump at eV =2 ∆ for ϕ �= 0. The differential conductivity dJ/dV has a singularity at eV =2 ∆ for ϕ �= 0. The relation J(V,ϕ )= −J(−V, ϕ + π )i s obtained.