This thesis presents systematic experimental research on chiral-lattice crystals referred to as B20-type germanium compounds, especially focusing on skyrmion spin textures and Dirac electrons. An emergent electromagnetic field observed in MnGe demonstrates a formation of three-dimensional skyrmion crystals. Detection of skyrmions in nanoscale Hall bar devices made of FeGe is realized by measuring the topological Hall effect, a transport property reflecting emergent fields produced by skyrmions. By measuring the electron-filling dependence of thermopower in CoGe, a pronounced thermoelectric property in this compound is revealed to stem from the asymmetric density of states appearing at certain levels of Fermi energy in the Dirac electron state. The three main results named above will contribute to enriching a variety of novel electromagnetic responses of emergent gauge fields in solids, to realizing high-performance skyrmion-based magnetic memory, and to designing high-efficiency thermoelectric materials, respectively.

Perhaps the title of this conference "Ctystalline Electric Field and Structural Effects in f-Electron Systems" reflects best the growth and direction of the field. The title and the conference itself go beyond "CEF" in two broad and important respects. First, the inter-relations between CEF and mode softenings, distortions due to quadruplar ordering or the Jahn Teller effect, have gained greater focus, hence the inclusion of . •• "Structral Effects. " Second, much greater emphasis on the actinides and, in particular, comparisons between actinides and the lighter rare earths is seen in this conference, hence the more general terminology . . . Iff-Electron Systems. " It seems clear that this comparison will lead to an extension to the actinides of mixed valence and Kondo considerations, as well as CEF effects. The emergence of a broader discipline which includes all f-electron systems and which is concerned with unstable, as well as stable, valence reflects the maturation of the field and a coming to grips with the complexity, as well as the unity, of f-electron systems. This maturation is also seen in the growing realization of the effects of CEF on transport, thermodynamic properties, and superconductivity and its co-existence with magnetic order. This volume contains 63 articles, all but two of which were presented at the Conference held in Philadelphia, U. S. A. , on 12-15 November, 1979. About 100 conferees from 13 countries attended the meeting which consisted of four full days of lecture presentations.

Recent advances in electrochemistry and materials science have opened the way to the evolution of entirely new types of energy storage systems: rechargeable lithium-ion batteries, electrochroms, hydrogen containers, etc., all of which have greatly improved electrical performance and other desirable characteristics. This book encompasses all the disciplines linked in the progress from fundamentals to applications, from description and modelling of different materials to technological use, from general diagnostics to methods related to technological control and operation of intercalation compounds. Designing devices with higher specific energy and power will require a more profound understanding of material properties and performance. This book covers the status of materials and advanced activities based on the development of new substances for energy storage.

The birth of this monograph is partly due to the persistent efforts of the General Editor, Dr. Klaus Timmerhaus, to persuade the authors that they encapsulate their forty or fifty years of struggle with the thermal properties of materials into a book before they either expired or became totally senile. We recognize his wisdom in wanting a monograph which includes the closely linked properties of heat capacity and thermal expansion, to which we have added a little 'cement' in the form of elastic moduli. There seems to be a dearth of practitioners in these areas, particularly among physics postgraduate students, sometimes temporarily alleviated when a new generation of exciting materials are found, be they heavy fermion compounds, high temperature superconductors, or fullerenes. And yet the needs of the space industry, telecommunications, energy conservation, astronomy, medical imaging, etc. , place demands for more data and understanding of these properties for all classes of materials - metals, polymers, glasses, ceramics, and mixtures thereof. There have been many useful books, including Specific Heats at Low Tempera tures by E. S. Raja Gopal (1966) in this Plenum Cryogenic Monograph Series, but few if any that covered these related topics in one book in a fashion designed to help the cryogenic engineer and cryophysicist. We hope that the introductory chapter will widen the horizons of many without a solid state background but with a general interest in physics and materials.

This book presents an investigation of the anomalous and topological Hall effects in some itinerant ferromagnets and helimagnets by measurements of Hall effects driven by electrical or heat current. New clarifications are provided for spin-dependent Hall effects induced by the Berry phase, skew scattering, and scalar spin chirality. The author reveals the scattering-free nature of the Berry-phase-induced anomalous Hall current by conducting the first comparative study of electrical and thermal Hall effects. The impurity-element dependence of the anomalous Hall effect caused by skew scattering is systematically investigated in the low-resistivity region for Fe. Two new examples showing a topological Hall effect are found in helimagnets, in which nonzero scalar spin chirality arises from the modulation of spin structure through Dzyaloshinsky–Moriya (DM) interaction. Such a DM-interaction-mediated topological Hall effect is a new type of topological Hall effect. Also the temperature dependence of topological Hall terms in the thermal Hall effect and Nernst–Ettingshausen effect is found to be totally different from that in the electrical Hall effect. These results will be useful for applications of spin current to devices with low power consumption.