Long range triplet Josephson effect through a ferromagnetic trilayer
By M. Houzet, A. Buzdin. 2007
162 citations recorded by the source corpus.
The coexistence of superconductivity and ferromagnetism is very rare in bulk systems. However, it can be easily achieved in artificially fabricated superconductor/ ferromagnet S/F heterostructures. The S/F proximity effect is characterized by the damped oscillatory behavior of the Cooper pair wave function in the ferromagnet. This phenomenon leads to nonmonotonic dependence of the critical temperature of S/F multilayers on the F layer thickness and the realization of Josephson junctions for a review, see Refs. 1 and 2. In the diffusive limit, the proximity effect in a F metal is rather short ranged due to the large value of the ferromagnetic exchange field. This is related to the incompatibility between singlet superconductivity and ferromagnetism. Interestingly, nonuniform magnetization can induce triplet superconducting correlations which are long ranged on the same scale as for the superconductor/normal N metal proximity effect. 3 Several experimental indications exist for this triplet proximity effect. 4,5 However, the transition from the usual to the long range triplet proximity effect has not been observed in the same system. In the present work, we investigate the conditions for the observation of the Josephson current due to a long range triplet component under controllable conditions. Noncollinear magnetization may serve as a source of the long range triplet component. However, it is not possible to have a Josephson current due to the interference of the triplet and singlet components. Two sources of triplet components are needed to observe the long range triplet Josephson effect between them. Thus, the simplest experimental realization of such a situation may be a S/F/F/F/S system with the magnetic moments of the F and F layers noncollinear with the F interlayer see Fig. 1. The optimal condition for triplet Josephson current observation is when the thicknesses dL and dR of the layers F and F are of the order of the coherence length f in the ferromagnet. Indeed, for large dL and dR, the triplet component is exponentially small due to the short range proximity effect in the layers F and F, while for very thin dL and dR, it is also small. Thus, we predict that the magnitude of the Josephson current in a structure with F layer thickness much larger than f will be comparable to that of a S/N/S junction with the same length. A similar phenomenon could be observed in lateral Josephson junctions made of a nanostructured ferromagnetic film, allowing control of its magnetic domain structure.
Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/b2071bf13a753e8d3c63b2a7be25260d32dc0b8d
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Citations in the corpus
- Superconducting spintronics (2015, result): “[101] Buzdin, A. & Koshelev, A. E. Periodic alternating 0- and π-junction structures as realization of φ-Josephson junctions.”
- Odd-frequency superconductivity (2017, background): “, 2009b) or multilayered magnetic structures (Houzet and Buzdin, 2007).”