Lecture

Vibrational Modes in Crystals

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In course

PHYS-310: Solid state physics II

Ce cours de deux semestres donne une introduction à la Physique du solide, à la structure cristalline, aux vibrations du réseau, aux propriétés électroniques, de transport thermique et électrique ainsi qu'aux propriétés magnétiques. Il se situe au niveau d ...

Description

This lecture covers the concept of vibrational modes in crystals, focusing on the Debye and Einstein models. It explains how these models approximate the vibrational energy density and heat capacity at different temperatures, emphasizing the contributions of acoustic and optical branches. The lecture also discusses the behavior of vibrational frequencies at high and low temperatures, highlighting the importance of considering the entire temperature range for accurate predictions.

Instructors (3)

Harald Brune

Originaire de Münich en Allemagne, né en 1961, Harald Brune obtient son diplôme en physique de l'Université Ludwig Maximilians en 1989. Après une thèse en chimie physique à l'Institut Fritz-Haber de la Société Max-Planck à Berlin il obtient son titre de docteur ès sciences en 1992. Dès cela, il rejoint le groupe du Prof. K. Kern à l'Institut de physique expérimentale à l'EPFL. En 1995 il est chercheur invité à Copenhague travaillant en modélisation chez le Prof. J. Nørskov. De retour à l'EPFL, il se voit décerné le prix Latsis EPFL 1996 pour ses études par microscopie à effet tunnel de processus atomiques déterminants la croissance cristalline de couches minces. En 1998 il obtient son habilitation (venia legendi) en Physique et est nommé Maître d'enseignement et de recherche (MER) en nanophysique à l'EPFL. La même année il recoit une offre de Professeur Ordinaire (C4) de l'Université Philipps de Marburg. Début 1999 il réfuse cette offre et accepte un poste de Professeur Extraordinaire à l'EPFL et s'installe au sein de l'Institut de la Physique des Nanostructures. Il est nommé Professeur Ordinaire en 2005. Sa recherche porte sur les propriétés physiques (en particulier le magnétisme et la structure électronique) de nouvelles formes de la matière condensée comme des nanostructures et des couches ultra-minces. Il s'intéresse également à la catalyse hétérogène sur des systèmes inspirés dans leur composition et taille par celle des sites actives dans les enzymes en biologie. Il enseigne la Physique Générale pour ingénieurs, la Physique des matériaux solides pour physiciens, les méthodes expérimentales pour physiciens, ainsi que la Physique des surfaces, interfaces et nanostrcutures à l'école doctorale.

Oleg Yazyev

Prof. Oleg Yazyev (Олег Язев) was born in Simferopol, Crimean peninsula. He obtained his degree in chemistry from Moscow State University in 2003. He then joined Ecole Polytechnique Fédérale de Lausanne (EPFL) completing his PhD thesis in chemistry and chemical engineering in 2007. Next two years he has spent as a postdoctoral fellow at the Institute of Theoretical Physics (ITP) and the Institute for Numerical Research in the Physics of Materials (IRRMA) of the same institution. In 2009-2011 he was a postdoctoral fellow at the Department of Physics of the University of California, Berkeley and the Lawrence Berkeley National Laboratory. In September 2011 he started an independent research group supported by the Swiss National Science Foundation professorship grant. In 2012 he was awarded an ERC Starting grant. His current research focuses on theoretical and computational physics of two-dimensional and topological materials with strong emphasis on their prospective technological applications. ResearcherID profile of Oleg Yazyev Google Scholar profile of Oleg Yazyev

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Related concepts (32)

Lecture

A lecture (from lēctūra ) is an oral presentation intended to present information or teach people about a particular subject, for example by a university or college teacher. Lectures are used to convey critical information, history, background, theories, and equations. A politician's speech, a minister's sermon, or even a business person's sales presentation may be similar in form to a lecture. Usually the lecturer will stand at the front of the room and recite information relevant to the lecture's content.

Gifford Lectures

The Gifford Lectures (ˈgɪfərd) are an annual series of lectures which were established in 1887 by the will of Adam Gifford, Lord Gifford. Their purpose is to "promote and diffuse the study of natural theology in the widest sense of the term – in other words, the knowledge of God." A Gifford lectures appointment is one of the most prestigious honours in Scottish academia. The lectures are given at four Scottish universities: University of St Andrews, University of Glasgow, University of Aberdeen and University of Edinburgh.

Heat capacity

Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat capacity is an extensive property. The corresponding intensive property is the specific heat capacity, found by dividing the heat capacity of an object by its mass. Dividing the heat capacity by the amount of substance in moles yields its molar heat capacity.

Specific heat capacity

In thermodynamics, the specific heat capacity (symbol c) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat that must be added to one unit of mass of the substance in order to cause an increase of one unit in temperature. The SI unit of specific heat capacity is joule per kelvin per kilogram, J⋅kg−1⋅K−1.

Temperature

Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called centigrade), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes.

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