Download or read book Electromagnetic, Magnetostatic, and Exchange-interaction Vortices in Confined Magnetic Structures written by Eugene Kamenetskii and published by . This book was released on 2008-01-01 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is currently much interest in studying vortex behaviors in different kinds of physical phenomena. Vortices can be easily observed in water. They are well recognized effects in plasma and atmospheric science. In vacuum, one can observe electromagnetic processes with broken symmetry characterizing by different topological effects. Manifestations of phase singularities in optical vortices have opened up a new frontier in optics. There is a large variety of vortex phenomena in condensed matter. It is well known that when a system consisting of many interacting particles is set rotating, it may form vortices. The concept of a vortex is at the center of our understanding of superfluidity. Vortices can appear in magnetically ordered structures and in Bose-Einstein condensates. In the vortex description, there can be used classical or quantum approaches. Vortices can or cannot carry the angular momentum. They can or cannot be characterized by some invariant, such as the flux of vorticity. In spite of the fact that vortices are in common occurrence in many physical problems, it seems very difficult at present to introduce an all-inclusive definition of such 'swirling' entities. Although not being an exhaustive treatise on vortices, this book intends to give a general overview on recent research topics on vortex phenomena in confined magnetic structures. In magnetic structures one can clearly distinguish three characteristic scales. There are the scales of the spin (exchange interaction) fields, the magnetostatic (dipole-dipole interaction) fields, and the electromagnetic fields. These characteristic scales may define different vortex states. It has been shown that in micrometer- or submicrometer-size ferromagnetic dots a magnetization vortex structure will be stable because of competition between the exchange and magnetic dipole interactions. Such magnetic vortices are topologically distinct and robust magnetic states. This stability has a potential as a unit cell for high density magnetic storage and magnetic logic devices. Magnetic vortex dynamics is closely related to their topological structure. One can observe chiral symmetry violation of the vortex states in ferromagnetic dots. A mechanism for changing the topological number of a magnetic configuration makes it possible to obtain controlled switching between the vortex structures. The influence of the vortices on the magnetization reversal was observed in thin ferromagnetic elements. There is a strong interest in study and implementation of vortex states in periodic arrays of magnetic dots. In dilute atomic Bose-Einstein condensates with spin degrees of freedom (the so-called spinor condensates), the anisotropic nature of the dipole interaction greatly enriches the dynamic properties of atoms. The interplay between the dipolar interaction and the spin exchange interaction may lead to the vortex state in the Bose-Einstein condensates that is analogous to the magnetic vortex found in thin magnetic films. Quantized vortices in BECs manifest the long-range phase coherence of many-particle quantum systems which are described by a complex-valued order parameter field, and their existence and stability is intimately related to the superfluid properties of the system. The dipole interaction provides us with a long-range mechanism of interaction. The importance of magnetostatic energy increases gradually as the magnetic structure size increases. Magnetostatic ferromagnetism has a character essentially different from exchange ferromagnetism. This statement finds strong confirmation in confinement phenomena of magnetic-dipolar-mode oscillations. In magnetic structures with the sizes from several micrometers up to tens of micrometers, one can observe peculiar magnetostatic (or magnetic-dipolar-mode) vortices. In quasi-2D magnetic-dipolar-mode ferrite disks two kinds of quantum-like conservation rules are encounted: the symmetry conservation and the double-valued-function electric flux quantization. The interplay between these conservation rules gives rise to unique vortex patterns. It is very interesting that together with the exchange-interaction and magnetic-dipolar vortex behaviors, electromagnetic (Poynting-vector) vortices can exist in ferromagnetic systems. A ferrite is a magnetic dielectric with low losses. This may allow for electromagnetic waves to penetrate the ferrite and results in an effective interaction between the electromagnetic waves and magnetization within the ferrite. At the ferromagnetic resonance conditions, such an interaction can demonstrate the electromagnetic vortex behaviors. One of the most exciting thing is that there can be found a certain resemblance between topological structures of phase singularities in quasi-2D electromagnetic and magnetization patterns. The book has 21 chapters. The chapters were written by top experts from 18 countries (Italy, Ukraine, UK, Mexico, USA, China, Germany, Brazil, Japan, Russia, France, Chile, Finland, Singapore, Greece, India, Canada, and Israel), who have contributed significantly to the advancement of the science and engineering of the magnetic vortex behaviors. I hope that the book will be a valuable aid to understand current studies in vortex phenomena in magnetic structures for scientists, researchers, and graduate students working in the field of electronic engineering, materials science, and condense matter physics. I would like to express my thanks to all of the authors who accepted my invitation to contribute the respective chapters. I would like to acknowledge Dr. S. G. Pandalai at Transworld Research Network for his invitation to me of editing this book. I would like to thank Prof. Reuven Shavit at the Electrical and Computer Engineering Department of Ben Gurion University of the Negev for his interest in new vortex behaviors in microwave magnetic systems, useful discussions, and valuable support in realization of this project. I would also like to thank my PhD student, Michael Sigalov, who is responsible in part for my scientific contribution to this book.