Ferromagnetic 0–<Emphasis Type="BoldItalic">π</Emphasis>
Josephson junctions |
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Authors: | M Weides H Kohlstedt R Waser M Kemmler J Pfeiffer D Koelle R Kleiner E Goldobin |
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Institution: | 1.Center of Nanoelectronic Systems for Information Technology (CNI),Research Centre Jülich,Jülich,Germany;2.Physikalisches Institut – Experimentalphysik II,Universit?t Tübingen,Tübingen,Germany |
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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.
PACS 74.50.+r; 74.78.Fk; 74.81.-g; 85.25.Cp |
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