Static charge-imbalance effects in intrinsic Josephson systems

Nonequilibrium effects created by stationary current injection in layered d-wave superconductors forming a stack of intrinsic Josephson junctions are studied. Starting from a nonequilibrium Green function theory we derive microscopic expressions for the charge-imbalance (difference between electron- and hole-like quasi-particles) on the superconducting layers and investigate its influence on the quasi-particle current between the layers. This nonequilibrium effect leads to shifts in the current-voltage curves of the stack. The theory is applied to the interpretation of recent current injection experiments in double-mesa structures.