Highly reproducible High Tc Josephson nanojunctions

J. LESUEUR; N. BERGEAL; M. SIRENA; M. APRILI; X. GRISON; G. FAINI; J. P. CONTOUR

Seattle, USA

Conferencia; Applied Superconductivity Conference, ASC; 2006

rather simple two-step process using ion irradiation. A microbridge 1 to 5 ìm wide is firstly designed by ion irradiating a c-axis-oriented YBa2Cu3O7 film through a gold mask such as the unprotected part becomes insulating. A lower Tc part is then defined within the bridge by irradiating with a much lower dose through a 20 wide narrow slit opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. Non hysteretic RSJ like behavior is observed, together with sinc Fraunhofer patterns for rectangular junctions. The IcRn product varies with temperature ; it can reach a few mV. The typical resistance ranges from 0.1 to a few ohms, and the critical current density can be as high as 30 kA/cm2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.2Cu3O7 film through a gold mask such as the unprotected part becomes insulating. A lower Tc part is then defined within the bridge by irradiating with a much lower dose through a 20 wide narrow slit opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. Non hysteretic RSJ like behavior is observed, together with sinc Fraunhofer patterns for rectangular junctions. The IcRn product varies with temperature ; it can reach a few mV. The typical resistance ranges from 0.1 to a few ohms, and the critical current density can be as high as 30 kA/cm2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.ìm wide is firstly designed by ion irradiating a c-axis-oriented YBa2Cu3O7 film through a gold mask such as the unprotected part becomes insulating. A lower Tc part is then defined within the bridge by irradiating with a much lower dose through a 20 wide narrow slit opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. Non hysteretic RSJ like behavior is observed, together with sinc Fraunhofer patterns for rectangular junctions. The IcRn product varies with temperature ; it can reach a few mV. The typical resistance ranges from 0.1 to a few ohms, and the critical current density can be as high as 30 kA/cm2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.2Cu3O7 film through a gold mask such as the unprotected part becomes insulating. A lower Tc part is then defined within the bridge by irradiating with a much lower dose through a 20 wide narrow slit opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. Non hysteretic RSJ like behavior is observed, together with sinc Fraunhofer patterns for rectangular junctions. The IcRn product varies with temperature ; it can reach a few mV. The typical resistance ranges from 0.1 to a few ohms, and the critical current density can be as high as 30 kA/cm2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.2. The dispersion in characteristics is very low, in the 5% to 10% range. Such nanojunctions have been used to make microSQUIDs operating at LN2 temperature. They exhibit a very small asymmetry, a good sensitivity and a rather low noise. The process is easily scalable to make rather complex Josephson circuits.