Josephson effect in cuprate superconducting structures

Abstract

Electron transport and microwave properties of cuprate superconducting structures (bicrystal junctions and hybrid mesa heterostructures) are discussed here. Superconducting current in junctions from cuprate superconductors with the dominant dx2−y2-wave symmetry is determined by the barrier properties, characterized by the mid-gap bound states due to the multiple Andreev reflection. In bicrystal junctions it is revealed via linear dependence of critical current density on square root of the transparency, and an increase of spectral density of shot noise at low voltages are observed. The experiments demonstrate that the superconducting hybrid mesa-heterostructures have the critical current density jс = 1–700 A/cm2 for an antiferromagnetic interlayer with thickness dM = 10–50 nm and the characteristic decay length of superconducting correlations on the order of 7 nm, due to the anomalous long range proximity effect, analyzed in the model of coupled superconductors via multilayer magnetic layer with antiferromagnetic ordering of magnetization in the layers. It is found that the hybrid mesa–heterostructures have much greater sensitivity to external magnetic field than conventional Josephson junctions because of the strong dependence of superconducting current on interlayer spin state.

Local and nonlocal shot noise in high-T superconducting nanowires

“…Extensive experimental work has been performed on studying mesoscopic d-wave superconductor structures (a review of which can be found in [13]). Additional experimental studies have probed current fluctuations and in particular the relation between shot noise and junction bias in mesoscopic d-wave structures [14,15,16]. These shot noise studies find strong agreement with the theoretical predictions derived in [17] which were based the scattering matrix approach.…”

How does the break-junction quasiparticle tunnel conductance look like for d-wave superconductors?

“…along the crystal c axis. Such a situation is realized, e.g., in mesas [52][53][54][55][56][57]. In this case, tunneling is predominantly incoherent [9], and it was considered by us earlier [58][59][60][61] with the special emphasis on the possible influence of the charge density wave (CDW) manifestations.…”