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Studies on the magnetic properties attributed to the competition with the magnetic interactions
http://hdl.handle.net/10935/3075
http://hdl.handle.net/10935/3075d3d23a70-d96f-48e3-a0ab-be3996c6f9df
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thesisK122-1.pdf
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thesisK122-2.pdf
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thesisK122-3.pdf (15.2 MB)
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thesisK122-4.pdf (1.8 MB)
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thesisK122_index.pdf (2.3 MB)
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| アイテムタイプ | default_学位論文 / Thesis or Dissertation(1) | |||||||||||
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| 公開日 | 2012-05-30 | |||||||||||
| タイトル | ||||||||||||
| タイトル | Studies on the magnetic properties attributed to the competition with the magnetic interactions | |||||||||||
| 言語 | en | |||||||||||
| 言語 | ||||||||||||
| 言語 | eng | |||||||||||
| 資源タイプ | ||||||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_db06 | |||||||||||
| 資源タイプ | doctoral thesis | |||||||||||
| アクセス権 | ||||||||||||
| アクセス権 | open access | |||||||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||||||
| その他（別言語等）のタイトル | ||||||||||||
| その他のタイトル | 相互作用の競合性に起因する特異な磁気的性質に関する研究 | |||||||||||
| 言語 | ja | |||||||||||
| 著者 |
倉田,早織
× 倉田,早織
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| 公開者 | ||||||||||||
| 出版者 | 倉田早織 | |||||||||||
| 言語 | ja | |||||||||||
| 抄録 | ||||||||||||
| 内容記述タイプ | Abstract | |||||||||||
| 内容記述 | In the natural world, there are various magnetic systems with a couple of competing interactions. We study what sort of magnetism has occurred depending on such coupling interactions concerning with following two cases. As the first case, two-dimensional square quantum Heisenberg antiferromagnets with competing interactions up to third neighbors (J1-J2-J3 model) are investigated by using the high temperature series expansion method. From the analyses of the wave-vector-dependent susceptibility χ(κ) and the static correlation function S(κ), we find four kinds of the stable paramagnetic phases in the critical temperature regions depending on the coupling constants, i.e., Neel, Collinear, and two helical paramagnetic phases, H1 and H2, which are characterized by the critical wave vector κCA(A=N, C, H1, or H2). Except around the H1-H2 phase boundary, the intermediate phases are shown in the neighborhood of the phase boundaries. The analogy between the paramagnetic phase diagram obtained here and the ordered ones derived by the simple spin wave theory, suggests the possibility of the spin liquid state in the ground state. The dynamical spectrum function F(κ. ω) is calculated in the form of Mori's continued fraction with the frequency moments. The dynamical aspects for the stable paramagnetic phases are also characterized by the critical wave vectorκCA. In the intermediate phase, the line shape undergoes slow change versus the wave vector κ. As the sceond case, the magnetic properties in the perovskite manganese oxide are investigated. The mother system LaMnO3 is a Mott insulator, and is observed to be layer-type antiferromagnetic state (A-type) by neutron-scattering experiments. We considered the effective Hamiltonian for the undoped insulating states within the Hartree-Fock approximation, which consists of the spin operator S and the pseudospin operator T for the orbital degree of freedom. We focus our attention on spin dynamics S(κ.ω), especially at the interplay between spin and orbital degrees. The results are compared with experimental date. | |||||||||||
| 言語 | en | |||||||||||
| 学位名 | ||||||||||||
| 学位名 | 博士(理学) | |||||||||||
| 言語 | ja | |||||||||||
| 学位授与機関 | ||||||||||||
| 学位授与機関識別子Scheme | kakenhi | |||||||||||
| 学位授与機関識別子 | 14602 | |||||||||||
| 学位授与機関名 | 奈良女子大学 | |||||||||||
| 言語 | ja | |||||||||||
| 学位授与年月日 | ||||||||||||
| 学位授与年月日 | 2000-03-24 | |||||||||||
| 学位授与番号 | ||||||||||||
| 学位授与番号 | 甲第122号 | |||||||||||
