SWEEP RATE EFFECTS AND MAGNETIZATION LOOPS OF BOTH HIGH-TEMPERATURE AND LOW-TEMPERATURE SUPERCONDUCTORS

We present an extensive study of the magnetization properties of high quality YBa2Cu3O7 and conventional low-temperature superconducting sin gle crystals using a vibrating sample magnetometer. The experimental c onditions cover a wide range of temperatures, applied fields (up to 30 T), and sweep rates. The experimentally measured linear relationship between the magnetization and the logarithm of the sweep rate is exami ned in detail. A simple picture of vortex motion as a combination of d rift and diffusion components provides a particularly useful model for analyzing the experimental results.