Sweep rate effects and magnetization loops of both high- and low-temperature superconductors

We present an extensive study of the magnetization properties of high quality YBa₂Cu₃O₇ and conventional low-temperature superconducting single crystals using a vibrating sample magnetometer. The experimental conditions 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 examined in detail. A simple picture of vortex motion as a combination of drift and diffusion components provides a particularly useful model for analyzing the experimental results.