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Universiẗat, Diss., 1999--Osnabrück.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16874号 / 工博第3595号 / 新制||工||1543(附属図書館) / 29549 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 一義, 教授 佐藤 啓文, 教授 梶 弘典 / 学位規則第4条第1項該当

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Nós obtemos o hamiltoniano associado ao modelo de oito vértices simétrico, tomando o limite de tempo contínuo em um modelo equivalente (modelo de Ashkin-Teller). O resultado é um hamiltoniano de Heisenberg com coeficientes Jx , Jy e Jz idênticos àqueles encontrados por Sutherland, na região crítica. A mudança nos operadores é acompanhada explicitamente e a relação entre o operador \"crossover\" do modelo de Ashkin-Teller e o operador energia do modelo de Baxter é obtida de forma transparente. / We obtain the associated Harniltonian for the symmetric eight-vertex model by taking the time-continuous limit in an equivalent Ashkin-Teller model. The result is a Heisenberg Hamiltonian with coefficients Jx , Jy e Jz identical to those found by Sutherland for choices of the parameters a, b, c and d that bring the model close to the transition. The change in the operators is accomplished explicitly, the relation between the crossover operator for the Ashkin-Teller model and the energy operator for the eight-vertex model being obtained in a transparent form.

Nós obtemos o hamiltoniano associado ao modelo de oito vértices simétrico, tomando o limite de tempo contínuo em um modelo equivalente (modelo de Ashkin-Teller). O resultado é um hamiltoniano de Heisenberg com coeficientes Jx , Jy e Jz idênticos àqueles encontrados por Sutherland, na região crítica. A mudança nos operadores é acompanhada explicitamente e a relação entre o operador \"crossover\" do modelo de Ashkin-Teller e o operador energia do modelo de Baxter é obtida de forma transparente. / We obtain the associated Harniltonian for the symmetric eight-vertex model by taking the time-continuous limit in an equivalent Ashkin-Teller model. The result is a Heisenberg Hamiltonian with coefficients Jx , Jy e Jz identical to those found by Sutherland for choices of the parameters a, b, c and d that bring the model close to the transition. The change in the operators is accomplished explicitly, the relation between the crossover operator for the Ashkin-Teller model and the energy operator for the eight-vertex model being obtained in a transparent form.

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(La0.67Sr0.33MnO3)£»(SrO), LSMO214(n=1) in short, is 2-D magnetic insulator with a structure very similar to the 3D La0.67Sr0.33MnO3 and La0.67Ca0.33MnO3, 113(n=1) in short, which consists of superstructure of a subsequent magnetic layers and insulating layers. Forming a single 214 phase bulk is not easy, a mix phase of 2<n<¡Û compounds is usually seen. In this project, our goal is to search the best growth condition by the traditional method by varying one growth parameter at a time and by the famous Taguchi methods which is based on the statistics and is proved in many systems a best way in studying the association between the film properties and the control factors. First part of this project, we change one growth condition at a time and find the film quality related with the growth condition. Second, we use ¡§Taguchi method¡¨ as bases to form a perpendicular table in which various growth conditions and levels are set. According the table, the number of experiments is limited down to nine. All of the films are examined by structure, electric and magnetic properties to formed the quality data base for films. The traditional method concludes that the higher growth temperature, lower total chamber pressure and high partial pressure ratio of Ar and Oxygen are the corrected way approaching to the single phase, 214, films. However, the result from Taguchi method is contradict to the tradition method, in which the high growth temperature, high total chamber pressure, low partial pressure ratio of Ar and oxygen and the medium RF forward power can approach to growth the single 214 phase film. All films consists mix phases of higher n. This may imply that the growth window for LSMO 214 is relative narrow that we did not set our condition right in that opening.