Correlation between ramp morphology and properties of ramp-type junctions

Abstract

The correlation between the morphology of ramps in YBazCus07-a thin films prepared by ionbeam etching and the properties of ramp-type junctions was investigated in detail. Ramp-type junctions were fabricated using PrBazCuz gGao 1 0 7 -6 as the barrier material. We examined the influence of different fabrication parameters on the ramp properties by Atomic Force Microscopy (AFM). Properties of junctions, which were fabricated by employing a postbaking of the etching mask, were compared with those of junctions prepared without any special treatment. Junctions containing the improved ramps showed I-V characteristics and a temperature dependence of the normal resistance RN typical for resonant tunneling.The other junctions, having also an order of magnitude lower values of RN, exhibited a metallic temperature dependence of RN, which can be possibly explained by contributions from metallic channels in the PrBazCuz 9Gao 1Q.i-6-barrier.

The current-phase relation in Josephson junctions

“…In SFS Josephson junctions, discussed in Sec. VII, the weak link is formed by a ferromagnetic metal placed 3 See Gubankov et al, 1985;Amatuni et al, 1987;Xu et al, 1990;Vengrus et al, 1994;Dö mmel et al, 1995;Kupriyanov and Tsai, 1995;Satoh et al, 1995Satoh et al, , 1998Wen et al, 1995;Verhoeven et al, 1996;Gerritsma et al, 1997;Horstmann et al, 1997Horstmann et al, , 1998Verbist et al, 1997;Yoshida et al, 1997;Sun and Gao, 2000;Yoshida, 2000. 4 See, for example, Imamura and Hasio, 1989;Benz, 1995;Benz and Burroughs, 1997;Sachse et al, 1997;Fritzsch et al, 1998Fritzsch et al, , 1999Whiteley et al, 1998;Lacquaniti et al, 1999Lacquaniti et al, , 2000Lacquaniti et al, , 2001Lacquaniti et al, , 2003Pö pel, Hagedorn, Buchholz, et al, 2000;Hadfield, Burnell, Booij, et al, 2001;Hadfield, Burnell, Kang, et al.…”

d-wave anisotropy and coexistence of the superconducting gap and pseudogap inLa2−xSrxMiyake1, Imaizumi2, Iguchi3 2003Phys. Rev. B9330View full textAdd to dashboardCite

“…Using the ramp-edge junction technique, we have recently developed a fabrication technique of high quality YBCO/Ag junctions capable of angle-resolved tunnel spectroscopy, which demonstrated the d x2-y2 -wave nature of YBCO superconductors. 16,17 The ramp-edge junction, 18,19 different from a conventional sandwich-type tunnel junction, relies on the formation of new fresh junction surface by an Ar ion milling process and in situ deposition of the counterelectrode, which yields junctions of high quality. 20 The angle-dependent tunnel gap structures and the formation of Andreev bound states are also expected for LSCO.…”

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.…”