Coupling of intrinsic Josephson junctions and subgap structure in the current–voltage characteristics of high-T_c superconductors

The subgap structure in current–voltage (I–V) characteristics of a stack of intrinsic Josephson junctions in high-T_c superconductors is studied. An analytical formula for the I–V characteristics is obtained which had taken into account the influence of the dynamically breaking of charge neutrality (DBCN) in CuO₂ layers on the subgap structure. It is shown that DBCN does not affect the positions and the amplitudes of the subgap peaks, but changes the curvature of the branches in the I–V characteristics. As a possible manifestation of the non-equivalence of the junction, the experimental I–V characteristics of intrinsic Josephson junctions are presented.

This paper was presented at the 8th International Superconductive Electronics Conference, Osaka, Japan, 19–22 June 2001.