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Spin-Wave Theory of Thermal Excitations and Inelastic Scattering in Heisenberg Magnets : New Developments in Compactification and Renormalization
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| Title: | Spin-Wave Theory of Thermal Excitations and Inelastic Scattering in Heisenberg Magnets : New Developments in Compactification and Renormalization |
| Other Titles: | Heisenberg 磁性体における熱励起と非弾性散乱のスピン波理論 : コンパクト化と繰り込みの新しい展開 |
| Authors: | 乗木, 優作 Browse this author |
| Issue Date: | 22-Mar-2018 |
| Publisher: | Hokkaido University |
| Abstract: | We propose a new scheme for modifying conventional spin waves so as to precisely describe low-dimensional Heisenberg magnets at finite temperatures. What is called the modified spin-wave theory was initiated by Takahashi, who intended to describe the low-dimensional ferromagnetic thermodynamics. There are various ways for modifying spin waves, especially, in ferrimagnets. Which magnetization should be kept zero, uniform, staggered, or both? One or more chemical potentials can be introduced so as to satisfy the relevant constraint condition either in diagonalizing the Hamiltonian or in minimizing the free energy. We can bring the thus-modified spin waves into interaction on the basis of the Hartree-Fock approximation or through the use of Wick's theorem in an attempt to refine their descriptions. Comparing various modification schemes, we eventually find an excellent bosonic language capable of describing heterogeneous quantum magnets on a variety of lattices over the whole temperature range -- Wick's-theorem-based interacting spin waves modified so as to keep every sublattice magnetization zero via the temperature-dependent Bogoliubov transformation. |
| Conffering University: | 北海道大学 |
| Degree Report Number: | 甲第13128号 |
| Degree Level: | 博士 |
| Degree Discipline: | 理学 |
| Examination Committee Members: | (主査) 教授 山本 昌司, 教授 根本 幸児, 講師 大原 潤, 助教 吉田 紘行 |
| Degree Affiliation: | 理学院（物性物理学専攻） |
| Type: | theses (doctoral) |
| URI: | http://hdl.handle.net/2115/73151 |
| Appears in Collections: | 課程博士 (Doctorate by way of Advanced Course) > 理学院(Graduate School of Science)
学位論文 (Theses) > 博士 （理学）
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