Ferromagnetic 0-pi Josephson junctions

Abstract

We present a study on low-$T_c$ superconductor-insulator-ferromagnet-superconductor (SIFS) Josephson junctions. SIFS junctions have gained considerable interest in recent years because they show a number of interesting properties for future classical and quantum computing devices. We optimized the fabrication process of these junctions to achieve a homogeneous current transport, ending up with high-quality samples. Depending on the thickness of the ferromagnetic layer and on temperature, the SIFS junctions are in the ground state with a phase drop either 0 or $\pi$. By using a ferromagnetic layer with variable step-like thickness along the junction, we obtained a so-called 0-$\pi$ Josephson junction, in which 0 and $\pi$ ground states compete with each other. At a certain temperature the 0 and $\pi$ parts of the junction are perfectly symmetric, i.e. the absolute critical current densities are equal. In this case the degenerate ground state corresponds to a vortex of supercurrent circulating clock- or counterclockwise and creating a magnetic flux which carries a fraction of the magnetic flux quantum ${\Phi }_0$.

5 pages, 5 figures

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Cited by in corpus (8)

• Spin-polarized supercurrents for spintronics: a review of current progress
• Detection of the phase shift from a single quantized superconducting vortex
• Magnetic interference patterns in 0-Pi SIFS Josephson junctions: effects of asymmetry between 0 and Pi regions
• Superconducting flux qubit with ferromagnetic Josephson $\pi$-junction operating at zero magnetic field
• Magnetization induced by odd-frequency spin-triplet Cooper pairs in a Josephson junction with metallic trilayers
• Magnetization Reversal by Tuning Rashba Spin-Orbit Interaction and Josephson Phase in a Ferromagnetic Josephson Junction
• Theoretical study of magnetism induced by proximity effect in a ferromagnetic Josephson junction with a normal metal
• Planar Josephson junctions for sensors and electronics:Different geometry, new functionality