Unconventional Superconductors

This book presents a theory for unconventional superconductivity driven by spin excitations. Using the Hubbard Hamiltonian and a self-consistent treatment of the spin excitations, the interplay between magnetism and superconductivity in various unconventional superconductors is discussed. In particular, the monograph applies this theory for Cooper-pairing due to the exchange of spin fluctuations to the case of singlet pairing in hole- and electron-doped high-Tc superconductors, and to triplet pairing in Sr2RuO4. Within the framework of a generalized Eliashberg-like treatment, calculations of both many normal and superconducting properties as well as elementary excitations are performed. The results are related to the phase diagrams of the materials which reflect the interaction between magnetism and superconductivity.

This book offers a comprehensive summary of experiments that are especially suited to reveal the order-parameter symmetry of unconventional superconductors. It briefly introduces readers to the basic theoretical concepts and terms of unconventional superconductivity, followed by a detailed overview of experimental techniques and results investigating the superconducting energy gap and phase, plus the pairing symmetry. This review includes measurements of specific heat, thermal conductivity, penetration depth and nuclearmagnetic resonance and muon-spin rotation experiments. Further, point-contact and tunnelling spectroscopy and Josephson experiments are addressed. Current understanding is reviewed from the experimental point of view. With an appendix offering five tables with almost 200 references that summarize the present results from ambient pressure heavy-fermion and noncopper-oxide superconductors, the monograph provides a valuable resource for further studies in this field.

This book presents the anisotropy and multiband effects in newly discovered unconventional superconductors: cuprate superconductors, borocarbides, magnezium-diboride and oxypnictides. The physical properties of these unconventional superconductors and the application of the two-band Ginzburg-Landau theory to these superconducting compounds are explained. Temperature dependencies of fundamental superconducting parameters are calculated using the GL theory taking into account multiband-and anisotropy effects. A comparision of theoretical results and experimental data is conducted. Additionally, the analytical solution of the microscopical Eliashberg theory and of the BCS theory is developed for two-band and anisotropic superconductors. Fluctuation effects in newly discovered superconductors are also discussed.

Presents a modern treatment of the physics of vortex matter, mainly applied to unconventional superconductors and superfluids but with extensions to other areas of physics.

This title gives a complete and detailed description of collective modes (CMs) in unconventional superfluids and superconductors (USC).

Physical Acoustics, Volume XX: Ultrasonics of High-Tc and Other Unconventional Superconductors covers the many acoustic studies of the high-Tc superconductors. This book is composed of 10 chapters that include some unconventional superconducting systems, such as superfluid 3He, heavy Fermion superconductors, and magnetic re-entrant superconductors. The introductory chapter summarizes the results that have been observed in Bardeen, Cooper, and Schriefer superconductors as functions both of temperature and magnetic field. The subsequent chapters deal with the theoretical and experimental aspects of ultrasonic study of some unconventional superconductors. Considerable chapters are devoted to the measurements with sound waves on the sintered high-Tc superconducting systems. These chapters examine first the temperature and magnetic field dependence of the velocity and elastic constants in sintered high-Tc superconductors, as well as the sound absorption and dispersion measurements on single crystals of these superconductors. Discussions on the small-sample resonant ultrasound technique that uses thin piezoelectric films and the effect of oxygen on superconducting properties and the response of sound to these additions are also provided in these chapters. The concluding chapter presents a theoretical foundation for sound measurements in the superconducting state, emphasizing the effects of multigap structures and gas anisotropy on sound attenuation in the superconducting state of the cuprate superconductors. This volume will be of great benefit to researchers in the fields of electronics technology and in applied and engineering mechanics.

Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.

This extensive and comprehensive handbook systematically reviews the basic physics, theory and recent advances in superconductivity. Covering the entire field, this unparalleled resource carefully blends theoretical studies with experimental results to provide an indispensable foundation for further research. Leading researchers, including Nobel laureates, describe the state of the art in conventional and unconventional superconductors. In addition to full-coverage of novel materials and underlying mechanisms, the handbook reflects continued, intense research into electron-phone based superconductivity.