Ferromagnetic 0–π Josephson junctions

Weides, M. , Kohlstedt, H., Waser, R., Kemmler, M., Pfeiffer, J., Koelle, D., Kleiner, R. and Goldobin, E. (2007) Ferromagnetic 0–π Josephson junctions. Applied Physics A: Materials Science and Processing, 89(3), pp. 613-617. (doi: 10.1007/s00339-007-4206-3)

Abstract

We present a study on low-Tc 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 of either 0 or π. By using a ferromagnetic layer with variable step-like thickness along the junction, we obtained a so-called 0–π Josephson junction, in which 0 and π ground states compete with each other. At a certain temperature the 0 and π 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 Φ0.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Weides, Professor Martin
• Authors: Weides, M., Kohlstedt, H., Waser, R., Kemmler, M., Pfeiffer, J., Koelle, D., Kleiner, R., and Goldobin, E.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Applied Physics A: Materials Science and Processing
• Publisher: Springer
• ISSN: 0947-8396
• ISSN (Online): 1432-0630
• Published Online: 07 August 2007