Determination of the spatial length scale of the magnetic field distribution in YBa2Cu3O7 ceramics and Bi2Sr2CaCu2O8 crystal

✍ Scribed by N. Bontemps; P.Y. Bertin; D. Davidov; P. Monod; C. Lacour; R. Even; V.V. Moshchalkov

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 244 KB
• Volume: 185-189
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)91030-8

✦ Synopsis

We have measured the EPR linewidth of a free radical layer as a function of height (0,28 to 10 gm) above the surface of an YBa2Cu307 superconducting ceramic. We find characteristic lengthscales of the order of 20-40 Ima for the field distri~fion at the surface.This result rules out the Abrikosov vortex lattice as the main source of surface EPR broadening, which we assign to extrinsic sources such as the grain structure. In contrast, the width of the free radical line, when deposited on the surface of a Bi2Sr2CaCu208 single crystal, exhibits a significant broadening only below the temperature where irreversibility sets in.