Contains report on one research project.Joint Service Electronics Program (Contract DAAL03-89-C-0001

Graybeal, John M.

Mankiewich, Paul M.

Nguyen, Paul

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Chapter 8. Consequences of Low-Dimensionality in Oxide SuperconductorsChapter 8. The Consequences of Low-Dimensionalityin Oxide SuperconductorsSponsorJoint Service Electronics Program (Contract DAAL03-89-C-0001)Academic and Research StaffProfessor John M. GraybealResearch AffiliatePaul M. MankiewichiGraduate StudentPaul NguyenThe goals of our project are: 1) to determinethe consequences of the low-dimensionalityof recently discovered high-Tc oxide super-conductors upon their superconductivity and2) to determine the significance of theirapplication for electronics. In recent mea-surements, strong evidence for thermally-ac-tivated vortex flux creep in high-quality filmmaterials in the presence of large appliedmagnetic fields has been observed.2 Thepresence of flux creep has important conse-quences for successful implementation inhigh-current-density electronic applications.In fact, recent measurements suggest thatthis flux creep may well be an important lim-iting factor in determining the critical currentdensity in presently fabricated "best-quality"materials.Flux creep may also play an important role inresistive transition where large applied mag-netic fields are present. Hence, current inter-pretations of experimental data may indeedunderestimate the true superconductingphase boundary in the presence of appliedfields. We therefore seek to determine thetrue superconducting phase boundary as afunction of temperature through careful mea-surements of the kinetic inductance inexternal applied magnetic fields.As our ability to fabricate these materialsprogresses, we seek to examine fundamentalquestions relevant to the usage of thesematerials in potential device configurations(including presently conceived three-terminalconfigurations). Because of the serioussurface quality problems associated with the"YBCO" (YBa 2Cu 307) materials due to theirprobability for losing oxygen, we have movedto the Bi-based "BSCCO" (Bi-Sr-Ca-Cu-O)materials which do not appear to suffer asgreatly from these problems. On this basis,we believe that an improved potential forforming the high-quality surfaces requisitefor device uses in this class of materials mayexist. We have recently had excellentsuccess in forming thin films of the 110 Kphase of BSCCO, and look forward toaddressing these issues in the near future.1 Director of Materials Research, Physics Department, Boston University, and AT&T Bell Laboratories, Holmdel.2 y. Yeshurun and A.P. Malozemoff, Phys. Rev. Lett. 60:2202 (1988); T.T.M. Palstra, et al., Phys. Rev. Lett.61:1662 (1988); J.D. Hettinger, A.G. Swanson, W.J. Skocpol, J.S. Brooks, J.M. Graybeal, P.M. Mankiewich, R.E.Howard, B.L. Straugh, and E.G. Burkhardt, "Flux Creep and High-Field Critical Currents in Epitaxial Thin Films ofYBa 2 CU3 0 7 ," Phys. Rev. Lett., submitted for publication.Professor Clifton G. Fonstad, Jr.52 RLE Progress Report Number 131

The Consequences of Low-Dimensionality in Oxide Superconductors

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The Consequences of Low-Dimensionality in Oxide Superconductors

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