Описание: The thesis presents experimental and theoretical results about the surface dynamics and the surface Dirac fermion (DF) spectral function of the strong topological insulators Bi2Te3 and Bi2Se3. The experimental results reveal the presence of a strong Kohn anomaly in the measured surface phonon dispersion of a low-lying optical mode, and the absence of surface Rayleigh acoustic phonons. Fitting the experimental data to theoretical models employing phonon Matsubara functions allowed the extraction of the matrix elements of the coupling Hamiltonian and the modifications to the surface phonon propagator that are encoded in the phonon self-energy. This allowed, for the first time, calculation of phonon mode-specific DF coupling ??(q) from experimental data, with average coupling significantly higher than typical values for metals, underscoring the strong coupling between optical surface phonons and surface DFs in topological insulators. Finally, to connect to experimental results obtained from photoemission spectroscopies, an electronic (DF) Matsubara function was constructed using the determined electron-phonon matrix elements and the optical phonon dispersion. This allowed calculation of the DF spectral function and density of states, allowing for comparison with photoemission and scanning tunneling spectroscopies. The results set the necessary energy resolution and extraction methodology for calculating ? from the DF perspective.
Описание: At the Material Research Society Spring 2013 meeting, held in San Francisco April 1-5, 2013, three symposia were held focusing on thermal-to-electric energy conversion and thermal transport: Symposium H: Nanoscale Thermoelectrics - Materials and Transport Phenomena - II, Symposium I: Materials for Solid-State Refrigeration, and Symposium V: Nanoscale Heat Transport - From Fundamentals to Devices.
Автор: Nolas G.S., Sharp J., Goldsmid J. Название: Thermoelectrics / Basic Principles and New Materials Developments ISBN: 354041245X ISBN-13(EAN): 9783540412458 Издательство: Springer Рейтинг: Цена: 26122.00 р. Наличие на складе: Есть у поставщика Поставка под заказ.
Описание: This book contains an in-depth analysis of thermoelectric theory, an overview of present day thermoelectric materials and devices, and as an updated source of information on the most studied recent thermoelectric materials developments. The main emphasis is on a basic understanding of the concepts and experimental techniques needed to propel researchers towards new and novel classes of thermoelectric materials with enhanced properties. The aim is to assist researchers in the field. The text is an expanded edition of a previous text "Electronic Refrigeration" by one of the authors, Julian Goldsmid. Half of the text is devoted to research that has taken place since the publication of that text. In addition, emphasis is placed on new materials research and developments.
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