Josephson effect in multiterminal superconductor-ferromagnet junctions coupled via triplet components

Article

关键词: SPIN-POLARIZED SUPERCURRENTS;    EXCHANGE FIELD;    CIRCUIT-THEORY;    CONDUCTANCE;   

DOI  :  10.1103/PhysRevB.93.104525

来源: SCIE

【 摘 要 】

On the basis of the Usadel equation we study a multiterminal Josephson junction. This junction is composed by magnetic superconductors S-m, which have singlet pairing and are separated from the normal n wire by spin filters so that the Josephson coupling is caused only by fully polarized triplet components. We show that there is no interaction between triplet Cooper pairs with antiparallel total spin orientations. The presence of an additional singlet superconductor S attached to the n wire leads to a finite Josephson current I-Q with an unusual current-phase relation. The density of states in the n wire for different orientations of spins of Cooper pairs is calculated. We derive a general formula for the current I-Q in a multiterminal Josephson contact and apply this formula for analysis of two four-terminal Josephson junctions of different structures. It is shown in particular that both the nematic and the magnetic cases can be realized in these junctions. In a two-terminal structure with parallel filter orientations and in a three-terminal structure with antiparallel filter orientations of the magnetic superconductors with attached additional singlet superconductor, we find a nonmonotonic temperature dependence of the critical current. Also, in these structures, the critical current shows a Riedel peak like dependence on the exchange field in the magnetic superconductors. Although there is no current through the S/n interface due to orthogonality of the singlet and triplet components, the phase of the order parameter in the superconuctor S is shown to affect the Josephson current in a multiterminal structure.

【 授权许可】

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