Mak Hon-lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves [105]-107). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgements --- p.iii / Contents --- p.iv / List of Figures --- p.vii / List of Tables --- p.x / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The origin of Heisenberg model --- p.1 / Chapter 1.2 --- High temperature superconductivity --- p.3 / Chapter 1.3 --- This project --- p.6 / Chapter Chapter 2. --- Studies of spin wave theory --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- The uniform antiferromagnetic Heisenberg Model --- p.9 / Chapter 2.2.1 --- Linearization --- p.11 / Chapter 2.2.2 --- Quadratic equation --- p.15 / Chapter 2.2.3 --- Quadratic equation with Constraint --- p.20 / Chapter 2.2.4 --- Other results --- p.24 / Chapter 2.3 --- The anisotropic Heisenberg model --- p.29 / Chapter 2.3.1 --- The uniaxial model --- p.29 / Chapter 2.3.2 --- The XY Ferromagnetic model --- p.31 / Chapter Chapter 3. --- Theoretical approach --- p.35 / Chapter 3.1 --- Classical ground state --- p.35 / Chapter 3.2 --- Quantum fluctuation --- p.37 / Chapter 3.2.1 --- Linear combination of operators --- p.42 / Chapter 3.3 --- Calculation of physical quantities --- p.44 / Chapter 3.3.1 --- Zero mode problem --- p.48 / Chapter Chapter 4. --- Results of unfrustrated systems --- p.52 / Chapter 4.1 --- Introduction --- p.52 / Chapter 4.2 --- Uniform system --- p.52 / Chapter 4.3 --- Missing bond case --- p.55 / Chapter 4.4 --- Vacancy case --- p.58 / Chapter 4.5 --- Ferromagnetic impurity case --- p.61 / Chapter 4.6 --- Antiferromagnetic impurity case --- p.65 / Chapter 4.7 --- Abnormal antiferromagnetic bond case --- p.68 / Chapter Chapter 5. --- Ferromagnetic bond case --- p.71 / Chapter 5.1 --- Origin of ferromagnetic bond --- p.71 / Chapter 5.2 --- Numerical results --- p.72 / Chapter 5.2.1 --- The classical results --- p.72 / Chapter 5.2.2 --- Quantum corrections --- p.75 / Chapter 5.3 --- Results of other schemes --- p.76 / Chapter 5.3.1 --- Spin wave approach --- p.76 / Chapter 5.3.2 --- Other approaches --- p.77 / Chapter Chapter 6. --- The transmittance pattern in a necklace like system --- p.80 / Chapter 6.1 --- Introduction --- p.80 / Chapter 6.2 --- The model --- p.81 / Chapter 6.3 --- Ring configuration --- p.82 / Chapter 6.4 --- Chain configuration --- p.86 / Chapter 6.5 --- The transmittance pattern --- p.87 / Chapter 6.5.1 --- Constant and varying flux --- p.89 / Chapter 6.5.2 --- Random flux --- p.91 / Chapter 6.5.3 --- Constant impurity --- p.93 / Chapter 6.5.4 --- Some random effects --- p.96 / Chapter 6.6 --- Summary --- p.98 / Chapter 6.7 --- "Appendix, Derivation of basic equations " --- p.100 / Chapter Chapter 7. --- Conclusion --- p.103 / Bibliography --- p.105

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 111-114).

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Thesis advisor: Kevin S. Bedell / In 1956, Lev Davidovich Landau put forth his theory on systems of interacting fermions, or fermi liquids. A year later, Viktor Pavlovich Silin described spin waves that such a system of fermions would support. The treatment of the contribution of the molecular field to the spin wave dispersion was a novel aspect of these spin waves. Silin predicted that there would exist a hierarchy of spin waves in a fermi liquid, one for each component of the spherical harmonic expansion of the fermi surface. In 1968, Anthony J. Leggett and Michael J. Rice derived from fermi liquid theory how the behavior of the spin diffusion coefficient of a fermi liquid could be directly experimentally observable via the spin echo effect. Their prediction, that the diffusion coefficient of a fermi liquid would not decay exponentially with temperature, but rather would have a maximum at some non-zero temperature, was a direct consequence of the fermi liquid molecular field and spin wave phenomena, and this was corroborated by experiment in 1971 by Corruccini, et al. A parallel advancement in the theory of fermi liquid spin waves came with the extension of the theory to describe weak ferromagnetic metals. In 1959, Alexei Abrikosov and I. E. Dzyaloshiski put forth a theoretical description of a ferromagnetic fermi liquid. In 2001, Kevin Bedell and Krastan Blagoev showed that a non-trivial contribution to the dispersion of the ferromagnetic current spin wave arises from the necessary consideration of higher harmonic moments in the distortion of the fermi surface from its ground state. In the chapters to follow, the author presents new results for transverse spin waves in a fermi liquid, which arise from a novel ground state of a fermi liquid--one in which an l=1 harmonic distortion exists in the ground state polarization. It is shown that such an instability can lead to spin waves with dispersions that are characterized by a linear dependence on the wave number at long wavelengths, or can lead to spin waves that are characterized by a square root dependence on the wave number at long wavelength. The author also presents new results for spin waves in a fermi liquid that has a spin density wave in its ground state. A spin density wave is characterized by a spiral magnetization in the ground state, and is observed to occur in materials such as MnSi. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

by Lee Kai Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references. / Acknowledgements --- p.II / Abstract --- p.III / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Theory --- p.7 / Chapter Chapter 3 --- Application of the Connected-Moments Expansion to the S=l/2 Heisenberg Antiferromagnet Paper I --- p.16 / Chapter Chapter 4 --- Application of the Connected-Moments Expansion to the Half-filled Hubbard Model Paper II --- p.18 / Chapter Chapter 5 --- Conclusion --- p.20 / Appendix I --- p.21 / Appendix II --- p.29 / References --- p.37

238 p. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mathematical Physics, 1974

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