The book comprises six chapters which deal with the critical currents and the ferromagnetism-superconductivity coexistence in high-Tc oxides. It begins by gathering key data for superconducting state and the fundamental properties of the conventional superconductors, followed by a recap of the basic theories of superconductivity. It then discusses the differences introduced by the structural anisotropy on the Ginzburg-Landau approach and the Lawrence-Doniach model before addressing the dynamics of vortices and the ferromagnetism-superconductivity coexistence in high-Tc oxides, and provides an outline of the pinning phenomena of vortices in these materials, in particular the pinning of vortices by the spins. It elucidates the methods to improve the properties of superconducting materials for industrial applications. This optimization aims at obtaining critical temperatures and densities of critical currents at the maximum level possible. Whereas the primary objective is the basic mechanisms pushing the superconductivity towards high temperatures, the secondary objective is to achieve a better understanding of the vortices pinning. This book is targeted at researchers and graduate students of fundamental and engineering sciences.
Table of Contents
Preface. Superconducting state. History of the superconductivity. Definition of a superconducting material. Meissner effect. Destruction of the superconductivity. Description of the superconducting state. Electronic specific heat. Electromagnetic absorption. Isotopic effect. Flux quantification. Josephson effects. References. Basis models. London model. Phenomenological theory of Ginzburg-Landau. BCS theory. References. High-Tc superconductor characteristics. Introduction. Cristallographic structures. Artificial multilayers. Physico-chemical properties. Elaboration process. References. Phenomenological theories of the anisotropic superconductors. Anisotropic Ginzburg-Landau model. Lawrence-Doniach model. References. Dynamic of vortices. Hysteresis origin in the magnetization curves. Breaking current of the Cooper pairs. Pinning force. Flux flow. Bean model. Flux creep. Thermally assisted flux flow. Irreversibility line. Magnetic instabilities. References. Interactions vortex-vortex, vortex defect and vortex-spin. Introduction. Elasticity theory of the vortices lattice. Different approaches of the vortices trapping. Critical currents. Lock-in transition. Pinning theory of Feigel’man, Geshkenbein et Larkin. Superconductivity and ferromagnetism Appendice. Demagnetizing fields. Physical quantities in SI and c.g.s.gauss systems. Some useful equations. References.