| Chapter One The brief history of the vortex dynamics of high temperature superconductors are reviewd. Some basic concepts and the important, theoretical models are introduced. The results and problems of those models on magnetic relaxation and the E-j relation are also introduced.Chapter Two The relation between the relaxation rate s and temperature T derived from the vortex-glass and the collective-creep model is compared with the experiment; moreover, considering backward hopping, the s-T relation derived from the thermal activated model are evaluated. In comparison of the theoretical results with the experimental data, it is found that the former models are in good agreement with the experiment at relatively low temperature regions, while the latter does at higher ones near T. These results are discussed in detail.Chapter Three The E-j relation of an HTSC slab is solved rigorously with respect to the situation that the system reach the equilibrium state under a large magnetic field, while considering backward hopping. Our results suggest and prove theoretically that the In E-lnj curves show ,positive curvatures. Moreover, whether or not p(j —> 0) reaches zero is also discussed.Chapter Four The E-j relation of an HTSC slab is solved rigorously with respect to the two different situations that the system does and does not reach the equilibrium state under the magnetic relaxation, while considering both forward and backward hopping. Our results suggest and prove theoretically that the In E-ln j curves show only positive curvature on the side of slab where the directions of current-created field and the applied field are the same, while they show both positive and negative curvatures at a certain field range on the other side where the directions are opposite. The relationship of the positive and negative curvatures with respect to the critical current, applied field and temperature is also discussed. Moreover, p(j —> 0) is further discussed.
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