YBa2Cu3Ox/PrBa2Cu3Ox/YBa2Cu3Ox Josephson ramp junctions

Abstract

A detailed study of the fabrication process, current voltage (I-V) characteristics, and Josephson and normal-state properties of the YBa2Cu3Ox(YBCO)/PrBa2Cu3Ox(PBCO)/YBCO ramp junctions is presented. The I-V characteristics can be well described by the resistively shunted junction model. It was found that the critical current Ic and the normal-state conductance 1/Rn scale linearly with the junction area, whereas Ic, the excess current Iex, and IcRn products decrease with increasing barrier thickness. These junctions with cross-sectional area A have a good controllability, low capacitance, and high values of IcRn and RnA products. The coherence length ξn of the PBCO barrier is estimated to be between 5 and 8 nm. As unambiguous evidence of the Josephson behavior, the microwave response as a function of the microwave power as well as the modulations of critical current Ic(H) with applied magnetic field are shown. A modulation depth of more than 95% has been observed. Small proximity effect parameters and junction capacitance (C/A∼10−7 F/cm2) show an advantage of these junctions for many applications.

Observation of the AC Josephson effect up to THz frequencies in YBCO/PBCO/YBCO ramp-type Josephson junctions

“…Nevertheless, a good fit is obtained, which shows that the high-frequency response of this junction can well be described by the RSJ model. This result agrees with the previously measured RSJ-like response of a ramp-type junction to 10 GHz radiation [8 ]. In the previously mentioned study using 176 GHz, the measured amplitudes of Ic and the first two Shapiro steps could be fitted nearly perfectly with a Bessel function, as is expected for a junction with Q > 1 [ 11 ].…”

“…In ramp-type junctions I~Rn at 4.2 K was found to vary from l to 8 mV, depending on the barrier thickness [ 8 ]. In a recent paper the transport mechanism and the reduction of the l~Rn product with increasing barrier thickness and temperature were analyzed [ 14 ].…”

“…The fabrication process for the ramp-type junctions has been described in detail in previous papers [ 7,8 ]. They show good scaling of their parameters with the cross-section area A, as well as a clear Josephson behavior.…”

Josephson tunneling of anisotropic high-Tcd-wave junctions with tiltedab-planeYBaArie1, Yasuda2, Kobayashi3 et al. 2000Phys. Rev. B364380View full textAdd to dashboardCite

“…In studies of high-T c Josephson junctions, there have been many measurements on the properties of the Josephson current using a bicrystal junction, 27,28 a ramp-edge junction, 29,30 or a step-edge junction. 31 There is also an intensive review article on the temperature dependence of the Josephson maximum current for high-T c SNS junctions.…”

Response of YBCO/PBCO/YBCO ramp type Josephson junctions to near mm wave irradiation

“…Design consideratations, the fabrication process of the junctions, and their scaling and Josephson properties have been discussed in detail [ 1,2,4].…”