Loading...
Please wait, while we are loading the content...
Similar Documents
Elliptical flux vortices in polycrystalline yba2cu3o7
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Chen, T. M. Hickman, H. |
| Copyright Year | 1990 |
| Description | The formation of an Abrikosov flux vortex with its core axis perpendicular to an anisotropic (a-c or b-c) plane in YBa2Cu3O7 requires only 1/10 of the energy required by the formation of a vortex with its core axis perpendicular to an isotropic (a-b) plane. It is not unusual for 18 to 35 percent of shake and bake bulk YBa2Cu3O7 to consist of empty pockets or voids inside the material. Studies estimate that 75 percent of the internal grain boundaries contain a-b planes. If many of the a-b planes are incident upon other grains, then many of the a-c and/or b-c planes must be incident on the voids. Evidently there are a large number of exposed anisotropic planes inside the bulk material. This condition is conducive to the formation of vortices that are perpendicular to the anisotropic planes. The magnetic flux density around such a vortex is constant along contour lines that are elliptical in shape, while the circulating supercurrent density must vary in magnitude along the same contour lines. The impact of this elliptical structure on the possibility of a Kosterlitz-Thouless type phase transition as the bulk material goes from superconducting to normal conducting is discussed. Implications with regard to the excess low frequency electrical noise that occurs at the temperature induced transition are also examined. |
| File Size | 40140 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19900018479 |
| Archival Resource Key | ark:/13960/t5fb9zs5c |
| Language | English |
| Publisher Date | 1990-04-01 |
| Access Restriction | Open |
| Subject Keyword | Solid-state Physics Grain Boundaries Magnetic Flux Superconductivity Polycrystals Abrikosov Theory Isotropy Flux Density Anisotropy Vortices Superconductors Materials Barium Oxides Copper Oxides Yttrium Oxides Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
