Coexistance of spin and charge density fluctuations in strongly correlated systems
| Autor: | Han, Fuxiang |
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| Rok vydání: | 1993 |
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| Druh dokumentu: | Thesis/Dissertation |
| Popis: | Spin and charge density fluctuations are important excitations in the strongly correlated systems, especially in the recently discovered high temperature superconductors. Several different theories on high temperature superconductors have been proposed based on spin fluctuations. However, experiments have also shown the existence of strong charge fluctuations. It is, therefore, desirable to investigate the physical consequences of the coexistence of strong spin and charge density fluctuations. As a first step toward a full understanding of both spin and charge excitations, a self-consistent theory is established. In this self-consistent theory, there are three important quantities, the spin susceptibility, the charge susceptibility, and the phonon Green's function. These three quantities are coupled together by the electron-phonon and phonon-spin fluctuation interactions. The phonon-spin fluctuation interaction is derived by making use of the spin-orbital coupling. For a strongly correlated system, the spin and charge density excitations have to be considered self-consistently. They are intimately related. The effects of antiparamagnons on phonons are also investigated. Antiparamagnons can have dramatic effects on phononic properties. It is found that new modes are formed in the presence of antiferromagnetic spin fluctuations. The de Haas-van Alphen effect in marginal and nearly antiferromagnetic Fermi liquids is studied. It is found that the de Haas-van Alphen frequency is unaffected by the anomalous response functions of the marginal and nearly antiferromagnetic Fermi liquids due to the absence of real parts of self-energies on the imaginary frequency axis. Graduation date: 1993 |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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