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arXiv · 0908.0303

Effects of Disorder in FeSe : An Ab Initio Study

Prabhakar P Singh
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Abstract

Using the coherent-potential approximation, we have studied the effects of excess Fe, Se-deficiency, and substitutions of S, Te on Se sub-lattice and Co, Ni and Cu on Fe sub-lattice in FeSe. Our results show that (i) a small amount of excess Fe substantially disorders the Fe-derived bands while Se-deficiency affects mainly the Se-derived bands, (ii) the substitution of S or Te enhances the possibility of Fermi surface nesting, specially in FeSe$_{0.5}$Te$_{0.5}$, in spite of disordering the Se-derived bands, (iii) the electron doping through Co, Ni or Cu disorders the system and pushes down the Fe-derived bands, thereby destroying the possibility of Fermi surface nesting. A comparison of these results with the rigid-band, virtual-crystal and supercell approximations reveals the importance of describing disorder with the coherent-potential approximation.

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Prabhakar P Singh. 2010-02-22. Effects of Disorder in FeSe : An Ab Initio Study. https://doi.org/10.1088/0953-8984%2F22%2F13%2F135501

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