The Property of Phonon Gap in Iron-Based Superconductors FeSe, LiFeAs and SrFeAsF

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• 作者：Wei Wang ; Bin Li ; Junqi He ; Jiafa Sun
• 关键词：First ; principles ; Iron ; based superconductor ; Phonon gap ; Filtering
• 刊名：Journal of Low Temperature Physics
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：186
• 期：5-6
• 页码：363-371
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Condensed Matter Physics; Characterization and Evaluation of Materials; Magnetism, Magnetic Materials;
• 出版者：Springer US
• ISSN：1573-7357
• 卷排序：186

文摘

First-principles calculations are performed for iron-based superconductors FeSe, LiFeAs and SrFeAsF, and the reasons of generation and loss of the phonon gaps in them are analyzed by analogy with electronic energy band theory. In iron-based superconductors FeSe and LiFeAs, lattice vibrations are affected by so strong changes in the periodic potential that the phonon spectra open a full gap. After considering electron–spin interactions, the enhancement of the periodic potential results in a broadening of the gap. From binary FeSe to ternary LiFeAs to quaternary SrFeAsF, the full phonon gap undergoes the process from decrease to disappearance, which is closely related to the frequencies overlapping of different atoms by vibrations. The fewer the material components and the larger the atomic number ratio, the more possible the production of the full phonon gap or the appearance of wider gap. In addition, the phonon gaps of FeSe and LiFeAs locate around the frequency of \(10^{12}\) Hz, whose filtering properties for elastic waves are hopefully to be applied in quantum acoustics.