Study of Josephson effects in microbridges of Bi-Sr-Ca-Cu-O films made by spray pyrolysis
Tóm tắt
Superconducting Bi-Sr-Ca-Cu-O (2212) films were prepared by spraying stoichiometric aqueous solutions of nitrates of bismuth, strontium, calcium and copper on heated MgO (100) substrates and subsequent annealing in air. TheR-T curves of the films show metallic behaviour above the superconducting transition temperature.T
c
(R=0) is observed between 80 and 85 K. Annealing temperature has a profound effect onT
c
(R=0) and on the orientation of the film. Annealing in air in near-melting region yields highly oriented films withc-axis perpendicular to the substrate. These films show a sharp superconducting transition with zero resistance at 85 K. Microbridges of the dimensions of 50 µm × 50 µm have been patterned photolithographically followed with chemical etching. The 1 V characteristics of the microbridges show Josephson effects due to the presence of grain boundary weaklinks. The temperature dependence of the critical current for these microbridges suggest formation of superconductor-normal-superconductor type weaklinks.
Tài liệu tham khảo
Ambegaokar V and Baratoff A 1963Phys. Rev. Lett. 10 486,11 4
de Gennes P G 1964Rev. Mod. Phys. 36 225
Mooney J B and Redding S B 1982Annu. Rev. Matter. Sci. 12 81
Reddy G S N, Gupta A K, Ojha V N, Walia D K, Kataria N D, Khare N and Tomar V S 1989Mod. Phys: Lett. B3 1311
Sears M W and Gee M A 1988Thin Solid Films 165 265
Setaka R, Komatsu W, Shibata T and Nakajima M 1988Jpn. J. Appl. Phys. 27 L2100
Walia D K, Gupta A K, Reddy G S N, Tomar V S, Kataria N D, Ojha V N and Khare N 1989Solid State Commun. 71 987