Flux-Pinning Properties of YBa2Cu3O7

Abstract
The flux-pinning properties of YBa2Cu3O7 semisingle crystalline films are investigated. The flux-pinning force density F p versus a reduced field b=H/H c2 * approximately obeys the formula, F pH c2 *n b p (1-b) q (n=2.6 –3.8, p∼0.7, q∼3.0), similarly to the case of the so-called weak-pinning type. Here, H c2 * is the upper critical field in a limit of zero current. The origin of F p is briefly discussed.