Studies of randomness effect in impurity scattering and spin interaction.

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.iiAcknowledgements --- p.iiiContents --- p.ivList of Figures --- p.viiList of Tables --- p.xChapter Chapter 1. --- Introduction --- p.1Chapter 1.1 --- The origin of Heisenberg model --- p.1Chapter 1.2 --- High temperature superconductivity --- p.3Chapter 1.3 --- This project --- p.6Chapter Chapter 2. --- Studies of spin wave theory --- p.7Chapter 2.1 --- Introduction --- p.7Chapter 2.2 --- The uniform antiferromagnetic Heisenberg Model --- p.9Chapter 2.2.1 --- Linearization --- p.11Chapter 2.2.2 --- Quadratic equation --- p.15Chapter 2.2.3 --- Quadratic equation with Constraint --- p.20Chapter 2.2.4 --- Other results --- p.24Chapter 2.3 --- The anisotropic Heisenberg model --- p.29Chapter 2.3.1 --- The uniaxial model --- p.29Chapter 2.3.2 --- The XY Ferromagnetic model --- p.31Chapter Chapter 3. --- Theoretical approach --- p.35Chapter 3.1 --- Classical ground state --- p.35Chapter 3.2 --- Quantum fluctuation --- p.37Chapter 3.2.1 --- Linear combination of operators --- p.42Chapter 3.3 --- Calculation of physical quantities --- p.44Chapter 3.3.1 --- Zero mode problem --- p.48Chapter Chapter 4. --- Results of unfrustrated systems --- p.52Chapter 4.1 --- Introduction --- p.52Chapter 4.2 --- Uniform system --- p.52Chapter 4.3 --- Missing bond case --- p.55Chapter 4.4 --- Vacancy case --- p.58Chapter 4.5 --- Ferromagnetic impurity case --- p.61Chapter 4.6 --- Antiferromagnetic impurity case --- p.65Chapter 4.7 --- Abnormal antiferromagnetic bond case --- p.68Chapter Chapter 5. --- Ferromagnetic bond case --- p.71Chapter 5.1 --- Origin of ferromagnetic bond --- p.71Chapter 5.2 --- Numerical results --- p.72Chapter 5.2.1 --- The classical results --- p.72Chapter 5.2.2 --- Quantum corrections --- p.75Chapter 5.3 --- Results of other schemes --- p.76Chapter 5.3.1 --- Spin wave approach --- p.76Chapter 5.3.2 --- Other approaches --- p.77Chapter Chapter 6. --- The transmittance pattern in a necklace like system --- p.80Chapter 6.1 --- Introduction --- p.80Chapter 6.2 --- The model --- p.81Chapter 6.3 --- Ring configuration --- p.82Chapter 6.4 --- Chain configuration --- p.86Chapter 6.5 --- The transmittance pattern --- p.87Chapter 6.5.1 --- Constant and varying flux --- p.89Chapter 6.5.2 --- Random flux --- p.91Chapter 6.5.3 --- Constant impurity --- p.93Chapter 6.5.4 --- Some random effects --- p.96Chapter 6.6 --- Summary --- p.98Chapter 6.7 --- "Appendix, Derivation of basic equations " --- p.100Chapter Chapter 7. --- Conclusion --- p.103Bibliography --- p.10