超電導材料におけるピンニング特性とその機構
1979 年 14 巻 6 号 p. 257-267
詳細
1979 年 14 巻 6 号 p. 257-267
This review article is concerned with the recent advances in the studies of the flux-line pinning. The fundamentals of the pinning mechanism are first explained briefly and next several methods to get a volume pinning force Fp caused by a random array of pins are described. The rigidity of the flux-line lattice is revealed to have important effects on the pinning characteristics. Two types of the flux-line motions are possible according to the lattice rigidity. The pinning force Fp is usually determined by the occurrence of a depinning flow, but sometimes in high magnetic fields it may be modified by the occurrence of a shearing flow.
Pinning properties in high-field superconductors are also summarized and discussed. It is shown that in usual cases the pinning force Fp obeys the scaling law, i. e. Fp∞[Bc2(T)]mf(b), where Bc2 is the 2nd critical field and f(b) is a function of the reduced magnetic field b=B/Bc2 only.
Finally, the effects of irradiations and stresses on the flux-line pinning are simply reviewed. The pinning properties of the compound superconductors are found to be more sensitive to irradiations and stresses than those of the alloy superconductors. It is mainly due to the high sensitivity of the critical temperatures to them in the compound superconductors.
