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Artigo Científico | Cerâmicas Supercondutoras | Inglês | 30/09/2001
Autores: Roberto Escudero
Palavras-chave: energy gap, high transition temperature, superconducting ceramics, superconductivity
Resumo: Some of the physical phenomena of the superconducting materials are the main topics of discussion in this chapter, particularly in the superconducting ceramics. Before to start the discussion and analysis of those characteristics, a small background is introduced, and this is related with the phenomenological bases of the superconducting state. After this, an introduction to the most important theoretical models to describe the superconducting state will be given. We will start with a thermodynamic description, after with London theory, to follow with the Ginzburg Landau theory and finaly with a brief introdution to the BCS weak coupling theory. The former will be useful to define the two types of superconductors: type I and II. To define this, we introduced two important parameters or lengths, which helps to define the superconducting state, the London penetration depth and the Ginzburg Landau coherence length. Important aspects related to the superconducting state of the ceramics will be discussed. Special emphasis is given in two experimental techniques: electron tunneling and point contact spectroscopy which are two spectroscopics tools which probes with particular detail the superconducting state, particularly the energy gap. These two experimental techniques may give enough information to start to have a better understanding of the physical mechanisms that couple electrons in the high temperature superconductors. At the end we will give some of the phenomenological aspects of the behavior of the normal state of the ceramics.
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