Superconducting Properties of Oxygen Deficient YBa2Cu3O7-δ
An important and interesting feature of the high temperature superconductor YBa2Cu3O7-δ is the dramatic effect of oxygen vacancies on its superconducting properties. 1–10 As oxygen is systematically removed from the structure, the orthorhombic distortion decreases and the system undergoes a structural transition to a tetragonal phase. Simultaneously, TC falls monotonically, with superconductivity disappearing at approximately the stoichiometry where the orthorhombic to tetragonal structural transition occurs. The curve of TC versus δ shows two regions of stable superconductivity where TC is not a strong function of δ. For δ near zero, there is a nearly flat region where TC is close to 90 K and for.35 < δ <. 45 there is a plateau where TC remains constant at approximately 60 K. The width of the inductive transition in these two regions is narrow suggesting that the superconductivity is due to a homogeneous well defined phase. In order to investigate the mechanisms and properties of superconductivity in YBa2Cu3O7-δ it is necessary to characterize and compare the superconducting behavior in these two phases. In this paper we present resistivity and magnetization data from which we determine the upper critical field Hc2 and compare the relative pinning strengths of polycrystalline samples with δ = 0.04 and 0.4.
KeywordsTwin Boundary Critical Field Superconducting Property Superconducting Transition Temperature Oxygen Stoichiometry
Unable to display preview. Download preview PDF.
- 1.W. K. Kwok, G. W. Crabtree, A. Umezawa, B. W. Veal, J. D. Jorgensen, S. K. Malik, L. J. Nowicki, A. P. Paulikas, L. Nunez, Phys. Rev. B 37 (Jan. 1988).Google Scholar
- 5.D. C. Johnston, A. J. Jacobson, J. M. Newsam, J. T. Lewandowski, D. P. Goshorn, D. Xie, and W. B. Yelon, Chemistry of High-Temperature Supercondncto.rs,edited by D. L. Nelson, M. S. Whittingham, and T. F. George, ( American Chemical Society, Washington, DC, 1987 ), p. 136.Google Scholar
- 9.M. Tokumoto, H. Ihara, T. Matsubara, M. Hirabayashi, N. Terada, H. Oyanagi, K. Murata, Y. Kimura, Jpn. J. Appl. Phys. 26, L1565(1987).Google Scholar
- 10.G. W. Crabtree, W. K. Kwok, H. Claus, B. W. Veal, J. D. Jorgensen,L. H. Nunez, A. Umezawa, A. P. Paulikas (to be published)Google Scholar
- 11.H. Claus, G. W. Crabtree, J. Z. Liu, W. K. Kwok, A. Umezawa, Proceedings of the MMM Conference, Nov.9–12, 1987, Chicago, IL., Journ. of Appl. Phys., (in press).Google Scholar
- 12.T. Tamegai, A. Watanabe, I. Oguro, Y. Iye, Jpn. J. Appl. Phys. 26, L1304(1987)Google Scholar
- 13.K. Hayashi, K. Murata, K. Takahashi, M. Tokumoto, H. Ihara, M. Hirabayashi, H. Terada, H. Koshizuka, Y. Kimura, Jpn. J. Appl.Phys. 26, L1240(1987)Google Scholar
- 14.Y. Iye, T. Tamegai, H. Takeya, H. Takei, Jpn. J. Appl. Phys. 26, L1057(1987)Google Scholar
- 15.T. Takabatake, M. Ishikawa, Y. Nakazawa, I. Oguro, T. Sakakibara, T. Goto, Jpn. J. Appl. Phys. 26, L978(1987)Google Scholar
- 16.J. S. Moodera, R. Meservey, J. E. Tkaczyk, C. X. Hao, G. A. Gibson, P. M. Tedrow (submitted to Phys. Rev. B)Google Scholar