Abstract In this work, electronic, magnetic and optical properties of Co-doped and (Co, Al) co-doped ZnS have been studied using the first principles technique based on density functional theory (DFT). The non-spin polarized state of ZnS changes to spin-polarized state when doping with Co. The Co ions interact antiferromagnetically which can be discussed on the basis of the super-exchange mechanism. The additional electron introduced by Al co-doping changes the magnetic order from antiferromagnetic to ferromagnetic state. Moreover, optical properties such as dielectric functions, reflectivity, absorption coefficients and transmissivity for undoped ZnS, Co; ZnS and (Co, Al); ZnS were also discussed. We found that the optical absorption edges shift to lower energy after Co doping in ZnS. After Al co-doping in Co; ZnS, a new peak is observed in infrared region. Thus, we found all curves of optical properties are broadened after Co doping and (Co, Al) co-doping in ZnS. The correlation between the magnetic coupling and intra-band d-d transition was also investigated and we found that d-d (4T1-6A1) transition peak for AFM coupled Co ions is higher than that for FM coupled Co ions, which is in line with theoretical and experimental observations. The improved optical and magnetic results indicate that (Co, Al) co-doped ZnS can be used as a promising candidate for photonic and spintronic devices in the future.

中文翻译：

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Co掺杂ZnS和(Al, Co)共掺杂ZnS的光电和磁性能的理论研究

摘要 在这项工作中，使用基于密度泛函理论 (DFT) 的第一性原理技术研究了 Co 掺杂和 (Co, Al) 共掺杂 ZnS 的电子、磁性和光学特性。掺杂 Co 时，ZnS 的非自旋极化状态变为自旋极化状态。 Co 离子反铁磁相互作用，这可以根据超交换机制进行讨论。Al共掺杂引入的额外电子将磁序从反铁磁状态改变为铁磁状态。此外，未掺杂的 ZnS、Co 的介电函数、反射率、吸收系数和透射率等光学特性；硫化锌和（钴，铝）；还讨论了硫化锌。我们发现在 ZnS 中掺杂 Co 后，光吸收边缘向较低能量移动。在 Co 中掺杂 Al 后；硫化锌，在红外区域观察到一个新峰。因此，我们发现在 ZnS 中 Co 掺杂和 (Co, Al) 共掺杂后，所有光学特性曲线都变宽了。还研究了磁耦合与带内dd跃迁之间的相关性，我们发现AFM耦合Co离子的dd（4T1-6A1）跃迁峰高于FM耦合Co离子的dd（4T1-6A1）跃迁峰，这符合理论和实验观察。改进的光学和磁性结果表明 (Co, Al) 共掺杂 ZnS 可用作未来光子和自旋电子器件的有希望的候选者。还研究了磁耦合与带内dd跃迁之间的相关性，我们发现AFM耦合Co离子的dd（4T1-6A1）跃迁峰高于FM耦合Co离子的dd（4T1-6A1）跃迁峰，这符合理论和实验观察。改进的光学和磁性结果表明 (Co, Al) 共掺杂 ZnS 可用作未来光子和自旋电子器件的有希望的候选者。还研究了磁耦合与带内dd跃迁之间的相关性，我们发现AFM耦合Co离子的dd（4T1-6A1）跃迁峰高于FM耦合Co离子的dd（4T1-6A1）跃迁峰，这符合理论和实验观察。改进的光学和磁性结果表明 (Co, Al) 共掺杂 ZnS 可用作未来光子和自旋电子器件的有希望的候选者。