Abstract
We theoretically study static and dynamic properties of short Josephson junctions (JJs) with singlet and triplet Josephson coupling. In singlet Josephson weak links, two singlet superconductors S are connected with each other by a normal film (N) or wire. Triplet JJs, which we denote -N(F)-, are formed by two singlet BCS superconductors covered by a thin layer of a weak ferromagnet . These superconductors are separated from the N (or F) layer by spin filters, which pass electrons with only one spin orientation. The triplet Cooper pairs propagating from the left (right) superconductors differ from each other not only in polarizations, but also in chiralities. The latter is determined by the magnetization orientation in weak ferromagnets . We obtain analytical formulas for the critical Josephson current in both types of JJs. If the chiralities of the triplet Cooper pairs penetrating into the N film in -N(F)- JJs from the left and right are different, the Josephson current is not 0 in the absence of the phase difference (spontaneous Josephson current). We also calculate the admittance for arbitrary frequencies in the case of singlet JJs and for low frequencies in the case of triplet JJs. At low temperatures , the real part of the admittance in singlet JJs starts to increase from 0 at , but at , it has a peak at low frequencies the magnitude of which is determined by inelastic processes. The subgap depends on the transparencies of the S/N interfaces and on the phase difference . The low-frequency peak in in triplet JJs disappears.
- Received 17 May 2017
DOI:https://doi.org/10.1103/PhysRevB.96.024517
©2017 American Physical Society