Spectral density approach to the double exchange model

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• 作者：Gangadhar Reddy ; G. ; Ramakanth ; A. ; Ghatak ; S.K.
• 关键词：71.10.Fd ; 75.30.MB ; 75.30.Vn ; D. Electronic structure ; D. Double exchange model ; A. Manganites ; A. Half-metal
• 刊名：Solid State Communications
• 出版年：2001
• 期刊代码：101_00381098
• 类别：ms
• 出版时间：October 16, 2001
• 卷：120
• 期：7-8
• 页码：325-329
• 文件大小：114 K

摘要

In rare-earth manganites the itinerant e_g-electrons interact via exchange coupling with localized t_2g-electrons which constitute the spin background. This fact is taken into account in the double exchange model DEM. The limit realistic to manganites is the strong coupling limit where the Hund's rule coupling constant between e_g- and t_2g-electrons is large compared to the e_g-hopping integral. The spectral density approach, a reliable scheme in the strong coupling limit, has been adopted to obtain the density of states DOS for the e_g-band. In this limit, the e_g-band splits into two bands with different weights for spin-up and spin-down states. In the ferromagnetic state, the effective band width of the split band depends on the spin state of the e_g-electron. Within the framework of the model and the approximation, it is observed that the temperature drives the half-metal to metal transition.