Solid State Theory - Institut für Theoretische und Angewandte Physik ...

14 J. Roth - Solid State Theory1987, became one of the most important subjects of research in condensed matterphysics, and continue to be at the center of interest at present.Finally, the last chapter is devoted to• Magnetic properties.Magnetism known to most people due to the surprising effects that arise from theinteraction among magnets and of magnets with paramagnetic metals, plays a veryimportant role in new technologies like information storage devices. It also playsa central role in high temperature superconductivity and other so-called stronglycorrelated materials, where the properties, many of them still to be understood,are determined by strong interelectronic interactions. We will give here a survey ofdifferent phenomena related to magnetism, and of theoretical techniques developedto describe them.It is hoped that at the end of these lectures, a broad view of Solid State Physicsis achieved, such that students will be prepared to start their own research project inone of the research groups at Stuttgart, where condensed matter physics constitutesa major area of research.Addition: A very important subject in Solid State Theory is the understandingof transport phenomena, such that we will have a chapter devoted to• Transport properties.In fact the easiest experiments are in general related to transport properties, likeelectrical and thermal transport. The difficulty here is that most of the experimentsare performed out of equilibrium, a regime where well establishes theories are notavailable. Therefore, we will consider semiclassical theories that will give us a generaland intuitive understanding of transport phenomena. This will be a contrast to theformal theory we discussed in the previous chapters and it is hoped that in this waystudents well have a broad perspective of theoretical techniques and ideas to tackleproblems in the future.