教師資料查詢 | 類別: 期刊論文 | 教師: 楊 棨 YAN, SHI (瀏覽個人網頁)

標題:High-temperature superconductivity in the generalized negative U Hubbard model
學年84
學期1
出版(發表)日期1995/11/05
作品名稱High-temperature superconductivity in the generalized negative U Hubbard model
作品名稱(其他語言)高溫超導在廣義負U Hubbard模型下之研究
著者Kocharian, A. N.; 楊棨; Yang, Chi
單位淡江大學物理學系
出版者Elsevier
著錄名稱、卷期、頁數Materials Chemistry and Physics 42(2), pp.134-137
摘要A new mechanism of superconductivity in high-temperature superconducting oxides (HTSCs) with partially occupied electrons in the p and d orbitals is proposed in the generalized negative U Hubbard model, including orbital degeneracy and the strong intra-atomic attraction. Our approach allows also the introduction, in a consistent way, of the orbital mixing (hybridization) between p and d bands (orbitals). The effective anisotropic Heisenberg XYZ model consisting of pseudo-orbital variables is obtained up to second order by small parameters for arbitrary concentration of particles using unitary transformation in the strong interaction limit. The ground-state energy and the partition function are obtained in the generalized mean field approximation by introducing diagonal charge-ordering parameter η and off-diagonal superconducting order parameter Δ. The self-consistent equations are analyzed and the phase diagram in the ground state and at finite temperatures for arbitrary relations between p and d bandwidths (parameter anisotropicity g) are obtained. The competition between superconducting and charge-ordering correlations for spin and orbital variables gives rise to many different pure and intermediate phases. The proposed model elucidates the role of hybridization and orbital variables on the mechanism of HTSC.
關鍵字Negative U Hubbard Hamiltonian;Mixed valence;Interacting fermions;Bipolaron superconductivity;Phase transitions
語言英文
ISSN0254-0584
期刊性質國內
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產學合作
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國別中華民國
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