Experimental Studies of Boson Fields in Solids (ePub)

This book provides a new understanding of the large amount of experimental results gained in solid state physics during the last seven decades. For more than 160 different materials, data analyses shown in terms of atomistic models (Hamiltonians) have not provided a quantitatively satisfactory description of either excitation spectra or dynamic properties. Instead, the experimental evidences have elaborated that field theories are necessary. However, most experimentalists are not familiar with field theories, and realistic field theories of magnetism are absent.The book illustrates in an empirical way the elements of future field theories of solid state physics with special emphasis on magnetic materials. In contrast to the many available textbooks on quantum field theories that emphasize more on algorithmic formalities rather than referring to the experimental facts, the approach in this book is pragmatic instead of abstract theoretic. This methodical concept considerably facilitates experimentalists to get acquainted with the basic ideas of field theories, even if a ready field theory is not provided by this experimental study.Contents: PrefaceIntroductionHistory of Conventional Spin Wave TheoryBasic Issues of Renormalization Group (RG) TheoryUniversalityMicroscopic ProcessesRelevant and Non-Relevant MagnonsCrossover PhenomenaMetastability of Universality ClassesRelevant and Non-Relevant InteractionsTemperature Dependence of the Magnon Excitation SpectraMagnetic Heat CapacityExperimental Verification of GSW BosonsMagnets With and Without Magnon GapMicroscopic Details: Spin Structure, Site Disorder, Two Order ParametersBoson Fields at the Magnetic Ordering TransitionThermal Lattice Expansion and MagnetostrictionBoson Fields Near Melting TransitionBoson Fields in SuperconductorsSummaryBibliographySubstance IndexReadership: Graduate students and researchers in condensed matter physics.Key Features:Presents a first review of the most revealing experiments in solid state physics made in the last seven decadesIllustrates the sharp limits of the atomistic descriptions by quantitative analyses of all these dataEmphasizes exclusively that the atomistic world view of solid state physics is inadequate and has to be replaced (or complemented) by field theories