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1
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84950599693
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edited by, T. Ishiguro, K. Kajimura, Springer Verlag, Tokyo
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(1990)
Advances in Superconductivity II
, pp. 335
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Sato, K.1
Hikata, T.2
Mukai, H.3
Masuda, T.4
Ueyama, M.5
Hitotsuyanagi, H.6
Mitsui, T.7
Kawashima, M.8
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3
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0026121319
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(1991)
IEEE Trans. Magn.
, vol.27 MAG
, pp. 1231
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Sato, K.1
Hikata, T.2
Mukai, H.3
Ueyama, M.4
Shibuta, N.5
Kato, T.6
Masuda, T.7
Nagata, M.8
Iwata, K.9
Mitsui, T.10
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6
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84927339291
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A.P. Malozemoff, Superconductivity and its Applications, AIP Conf. Proc. No. 251, edited by Y.H. Kao et al. (American Institute of Physics, New York, 1992), p. 6.
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8
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36449007730
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Y. Feng, Y.E. High, D.C. Larbalestier, Y.S. Sung, and E.E. Hellstrom, Appl. Phys. Lett. 62, 1553, 1993.
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(1993)
Appl. Phys. Lett.
, vol.62
, pp. 1553
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Feng, Y.1
High, Y.E.2
Larbalestier, D.C.3
Sung, Y.S.4
Hellstrom, E.E.5
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10
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84927339290
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The condition for the Josephson interlayer coupling is ξz ll s, where ξz is the superconducting correlation length along c axis and s is the interlayer spacing. This condition can be rewritten in the form (Tc-T)/Tc gg ξab2(0)/γ2s2 where ξab(T) is the correlation length in the ab plane and γ is the anisotropy ratio. For Bi Compounds ξab(0) approx 25 AA and s=15 AA for Bi 2:2:1:2 and 18 AA for Bi 2:2:2:3. The anisotropy ratio for Bi 2:2:2:3 is about 30 according to Hc2 measurements near Tc;
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12
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84927339289
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This value is probably a lower limit for γ. For Bi 2:2:1:2 a lower limit for the anisotropy ratio at high temperatures seems to be about 200;
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13
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84927292213
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Phys. R, 69, 2276 (1992) and Y. Iye
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(1992)
Physica C
, vol.199
, pp. 154
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Martinez, J.C.1
Brongersma, S.H.2
Koshelev, A.3
Ivlev, B.4
Kes, P.H.5
Griessen, R.P.6
de Groot, D.G.7
Tarnavski, Z.8
Menovsky, A.A.9
Lett10
Oguro, I.11
Tamegai, T.12
Datars, W.R.13
Motohira, N.14
Kitazawa, K.15
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14
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84927339288
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Therefore, the Josephson regime is important practically at all temperatures below Tc in the Bi compounds.
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15
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84927339287
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It is also possible that impurities present during the fabrication process tend to concentrate preferentially along a and b axis boundaries outside of colony boundaries, further weakening those weak links.
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37
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36449007811
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(1992)
Appl. Phys. Lett.
, vol.60
, pp. 2306
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Thompson, J.R.1
Sun, Y.R.2
Kerchner, H.R.3
Christen, D.K.4
Sales, B.C.5
Chakoumakos, B.C.6
Marwick, A.D.7
Civale, L.8
Thompson, J.O.9
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42
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84927339281
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The pinning energy of a single pancake vortex by a columnar defect can be estimated as the core energy of a 2D vortex. This energy is approxΦ0sup 2s/16π2λab2, where λab is the penetration depth for the current along the ab plane. For s=18 AA, λab=2000 AA we obtain an energy close to 70 meV.
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43
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84927339279
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We note that in tapes a and b axis weak links and secondary phase boundaries are equivalent to columnar defects from the point of view of pinning because the superconducting order parameter is strongly reduced inside these boundaries. However, the concentration of such defects is quite small in comparison to the number of intragranular defects. For this reason is probably reasonable to neglect the effect of these defects. In fact, the influence of grain boundaries on the critical current was not found in the case of textured Bi 2:2:1:2 bulk samples as compared with epitaxial films; see Ref. onlineciteschmitt.
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44
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0343495991
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(1992)
J. Appl. Phys.
, vol.72
, pp. 2951
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Yamasaki, H.1
Endo, K.2
Nakagawa, Y.3
Umeda, M.4
Kosaka, S.5
Misawa, S.6
Yoshida, S.7
Kajimura, K.8
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48
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84927339271
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Note that we calculated the thermodynamical critical current which can be probed by static measurements. In the presense of transport current through the junction at nonzero temperature the voltage should appear at any current due to vortex fluctuations. For finite junction without vortices similar effect was calculated by Ambegaokar and Halperin;
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51
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84927339270
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W.E. Lawrence and S. Doniach, in Proceedings of the 12th International Conference on Low Temperature Physics, Kyoto 1970, edited by E. Kanda (Keigaku, Tokyo, 1970).
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53
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84927339269
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The thermal averaging of the current is an exact procedure. In the case of disorder caused by pinning centers, the average current may not be very significant if the current fluctuations are large. The latter are certainly important when the average current becomes very small, as in the case for the Fraunhofer dependence of the critical current on a magnetic field parallel to the junction;
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55
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0001235373
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Here we consider only the case of a sufficiently large critical current so that the effect of fluctuations can be ignored. This approximation is correct because many uncorrelated weak links contribute to the total current.
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(1970)
Sov. Phys. JETP
, vol.31
, pp. 800
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65
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84927339268
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The account of the vortex fluctuations should make this value smaller;
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70
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43949168560
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(1993)
Physica C
, vol.209
, pp. 167
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Caplin, A.D.1
Cassidy, S.M.2
Cohen, L.F.3
Cuthbert, M.N.4
Laverty, J.R.5
Perkins, G.K.6
Dou, S.X.7
Guo, Y.C.8
Liu, H.K.9
Tao, H.J.10
Wolf, E.L.11
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