Spontaneous Currents in Josephson Devices

Abstract

The unconventional Josephson coupling in a ferromagnetic weak link between d-wave superconductors is studied theoretically. For strong ferromagnetic barrier influence, the unconventional coupling, with ground state phase difference across the link $0<{\varphi }_{\mathrm{gs}}\le \pi$, is obtained at small crystal misorientation of the superconducting electrodes, in contrast to the case of normal metal barrier, where it appears at large misorientations. In both cases, with decreasing temperature there is an increasing range of misorientations, where ${\varphi }_{\mathrm{gs}}$ varies continuously between 0 and $\pi$. When the weak link is a part of a superconducting ring, this is accompanied by the flow of spontaneous supercurrent, of intensity which depends (for a given misorientation) on the reduced inductance $l=2\pi L{I}_c(T)/{\Phi }_0$, and is non-zero only for $l$ greater than a critical value. For $l\gg 1$, another consequence of the unconventional coupling is the anomalous quantization of the magnetic flux.

8pages, 6figures, To be published in Phys. Rev. B {\bf 60} (1 september 1999-I)

References in corpus (1)

• Pinhole junctions in d-wave superconductors

Cited by in corpus (5)

• Proximity effects in superconductor-ferromagnet heterostructures
• Josephson currents through spin-active interfaces
• Supercurrent in Long SFFS Junctions with Antiparallel Domain Configuration
• Quasiparticle energy spectrum in ferromagnetic Josephson weak links
• Proximity-induced minimum radius of superconducting thin rings closed by the Josephson 0 or pi junction