Effects of d-wave symmetry in high-T_C grain boundary Josephson junctions

摘要

Recent experimental results on the physics of high temperature superconductivity (HTS) related to coherent phenomena and unconventional pairing symmetry are discussed. Some consequences of the d-wave order parameter symmetry on the phenomenology of HTS junctions of different type are investigated. The attention is focused on recent experiments based on biepitaxial YEa_2Cu_3O_(7-δ)Josephson structures where junctions with a π shift in the phase have been reproducibly obtained. Anisotropy measurements confirm the relevance of effects of d-wave order parameter symmetry on the properties of the junctions, and prove that intrinsic d-wave effects can be predominant over extrinsic effects. The possibility to obtain some kind of tunnel-like barriers and to tune d-wave effects through a suitable geometry has been demonstrated opening some perspectives towards novel device concepts within the framework of π circuitry and "quiet qubit".