Ab-initio optical properties and dielectric response of open-shell spinel zinc ferrite

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• 作者：Vafa Ziaei ; Thomas Bredow
• 关键词：Solid State and Materials
• 刊名：The European Physical Journal B
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：90
• 期：2
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Condensed Matter Physics; Physics, general; Complex Systems; Fluid- and Aerodynamics; Solid State Physics;
• 出版者：Springer Berlin Heidelberg
• ISSN：1434-6036
• 卷排序：90

文摘

In the present work, we predict the optical properties and the dielectric response spectrum of the spinel zinc ferrite Zn₂Fe₄O₈, and show in particular the impact of many-body effects on the absorption spectrum, using advanced many-body perturbation approach. The excitonic effects remarkably redistribute the spectral weights causing a red-shift of 1.6 eV of the maximum of the independent particle G₀W₀ (IP-G₀W₀) towards the electron-hole affected spectrum. The excitation spectrum of the zinc ferrite exhibits a low lying doubly degenerated bound dark exciton at 1.84 eV with a fully symmetric excited-state density, and a narrow optical gap setting on at 1.93 eV. We further analyse the electronic transitions and exciton density distributions giving insights to the nature of excitations. The dielectric response of Zn₂Fe₄O₈ shows a particular sensitivity to the excitations higher than the electronic band gap, however it abruptly becomes passive to the incoming electro-magnetic wave and propagates to the negative regions at high energy regimes.