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Spintronic devices utilize the electron charge and spin degree of freedom to achieve novel quantum functionalities. Diluted magnetic semiconductors (DMS) constitute an important category of spintronic materials that have the potential to be successfully incorporated into the existing semiconductor industry. The prototypical DMS (Ga,Mn) As, discovered in the 1990s, accomplishes spin and charge doping simultaneously through the heterovalent substitution of the magnetic ion Mn2+ for Ga3+. Two challenges have presented themselves in this material. First, the heterovalent nature of this integrated spin/charge doping results in severely limited chemical solubility in (Ga,Mn) As, restricting specimen fabrication to metastable thin films by molecular beam epitaxy; second, the simultaneous spin and charge doping precludes the possibility of individually tuning the spin and charge degree of freedom. A new type of ferromagnetic DMS based on I-Ⅱ-V group can overcome both of these challenges. Li(Zn,Mn) As utilizes excess Li concentration to introduce hole carriers, while independently making the isovalent substitution of Mn2+ for Zn2+ in order to achieve local spin doping. With no heterovalent substitution to restrict chemical solubility, bulk samples of Li(Zn,Mn) As are successfully fabricated. However, one drawback of Li(Zn,Mn) As is its use of the toxic element As. The isostructural direct-gap semiconductor LiZnP also undergoes a ferromagnetic transition upon Mn doping, and its bulk magnetic properties are very similar to those of LiZnAs. In this paper, the geometric structure of pure LiZnP, Ag doped, Cr doped, and Ag-Cr co-doped LiZnP new diluted magnetic semiconductor are optimized by using the first-principles plane wave ultra-soft pseudo-potential technology based on the density function theory. Then we calculate the electronic structure, magnetism, formation energy, differential charge density, and optical properties of the doped systems. The results show that the material is a paramagnetic metal after single doping of the nonmagnetic element Ag. When magnetic element Cr is doped with LiZnP, sp-d orbital hybridization makes the peak of density of state nearly EF-split, leading the system to become metallic ferromagnetism. However, Ag-Cr co-doped LiZnP changes into half-metallic ferromagnetism, which is completely different from the single doping system. The band gap decreases slightly, and the electrical conductivity is enhanced. Meanwhile, the formation energy of the system becomes lower, the bond between atoms strengthens, and the stability of the unit cell becomes stronger. A comparison of the optical properties indicate that the imaginary part of dielectric function and the optical absorption spectrum both present new peaks in low energy region in the doped systems. Ag-Cr co-doped LiZnP has the highest dielectric peak. Meanwhile, the complex refractive index function changes obviously in a low energy region, and the absorption edge extends to the low energy direction. The system enhances the absorption of low-frequency electromagnetic waves.
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Keywords:
- AgCr co-doped LiZnP /
- electronic structures /
- magnetism /
- optical properties
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[21] Chen K, Fan G H, Zhang Y, Ding S F 2008 Acta Phys. Sin. 57 3138 (in Chinese) [陈琨, 范广涵, 章勇, 丁少锋 2008 物理学报 57 3138]
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[23] Wen P, Li C F, Zhao Y, Zhang F C, Tong L H 2014 Acta Phys. Sin. 63 197101 (in Chinese) [文平, 李春福, 赵毅, 张凤春, 童丽华 2014 物理学报 63 197101]
[24] Ru Q, Li Y L, Hu S J, Peng W, Zhang Z W 2012 Acta Phys. Sin. 61 038210 (in Chinese) [汝强, 李燕玲, 胡社军, 彭薇, 张志文 2012 物理学报 61 038210]
[25] Duan M Y, Xu M, Zhou H P, Shen Y B, Chen Q Y, Ding Y C, Zhu W J 2007 Acta Phys. Sin. 56 5359 (in Chinese) [段满益, 徐明, 周海平, 沈益斌, 陈青云, 丁迎春, 祝文军 2007 物理学报 56 5359]
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[1] Zhao J H, Deng J J, Zheng H Z 2007 Prog. Phys. 27 109 (in Chinese) [赵建华, 邓加军, 郑厚植 2007 物理学进展 27 109]
[2] Wang Y, Zhan Y Z, Xu Y F, Yu Z W 2007 Mate. Rev. 21 20 (in Chinese) [王颖, 湛永钟, 许艳飞, 喻正文 2007 材料导报 21 20]
[3] Deng Z, Zhao K, Jin C Q 2013 Physics 10 682 (in Chinese) [邓正, 赵侃, 靳常青 2013 物理 10 682]
[4] Maek J, Kudrnovsky J, Mca F, Gallagher B L, Campion R P, Gregory D H, Jungwirth T 2007 Phys. Rev. Lett. 98 067202
[5] Deng Z, Jin C Q, Liu Q Q, Wang X C, Zhu J L, Feng S M, Chen L C 2011 Nat. Commun. 2 422
[6] Wang A L, Wu Z M, Wang C, Hu A Y, Zhao R Y 2013 Acta Phys. Sin. 62 137101 (in Chinese) [王爱玲, 毋志民, 王聪, 胡爱元, 赵若禺 2013 物理学报 62 137101]
[7] Qin C 2013 M. S. Thesis (Hangzhou: Zhejiang University) (in Chinese) [秦川 2013 硕士学位论文 (杭州: 浙江大学)]
[8] Jairo Sinova J, Maek J, Kučera J, MacDonald A H 2006 Rev. Mod. Phys. 78 809
[9] Ding C, Man H Y, Qin C, Lu J C, Sun Y L, Wang Q, Yu B Q, Feng C M, Goko T, Arguello C J, Liu L, Frandsen B A, Uemura Y J, Wang H D, Luetkens H, Morenzoni E, Han W, Jin C Q, Munsie T, Williams T J, D'Ortenzio R M, Medina T, Luke G M, Imai T, Ning F L 2013 Phys. Rev. B 88 041102
[10] Guan Y Q, Chen Y, Zhao C W 2010 Mat. Sci. Eng. Pow. Met. 15 521 (in Chinese) [关玉琴, 陈余, 赵春旺 2010 粉末冶金材料科学与工程 15 521]
[11] Cui X Y, Medvedeva J E, Delley B, Freeman A J, Newman N, Stampfl C 2005 Phys. Rev. Lett. 95 256404
[12] Lin Z, Guo Z Y, Bi Y J, Dong Y C 2009 Acta Phys. Sin. 58 1917 (in Chinese) [林竹, 郭志友, 毕艳军, 董玉成 2009 物理学报 58 1917]
[13] Wu Z H, Xie H Q, Zen Q F 2013 Acta Phys. Sin. 62 097301 (in Chinese) [吴子华, 谢华清, 曾庆峰 2013 物理学报 62 097301]
[14] Deng J Q, Wu Z M, Wang A L, Hu A Y, Zhao R Y 2014 Comp. Phys. 31 617 (in Chinese) [邓军权, 毋志民, 王爱玲, 胡爱元, 赵若禺 2014 计算物理 31 617]
[15] Chen B J, Deng Z, Li W M, Gao M, Zhao J F, Zhao G Q, Yu S, Wang X C, Liu Q Q, Jin C Q 2016 Aip. Adv. 6 115014
[16] Wei S H, Zunger A 1986 Phys. Rev. Lett. 56 528
[17] Kuriyama K, Nakamura F 1987 Phys. Rev. B 36 4439
[18] Segall M D, Lindan P J D, Probert M J, Pickard C J, Hasnip P J, Clark S J, Payne M C 2002 Phys. Cond. Mat. 14 2717
[19] Vanderbilt D 1990 Phys. Rev. B 41 7892
[20] Monkhorst H J, Pack J D 1976 Phys. Rev. B 13 5188
[21] Chen K, Fan G H, Zhang Y, Ding S F 2008 Acta Phys. Sin. 57 3138 (in Chinese) [陈琨, 范广涵, 章勇, 丁少锋 2008 物理学报 57 3138]
[22] Guan L, Li Q, Zhao Q S, Guo J X, Zhou Y, Jin L T, Geng B, Liu B T 2009 Acta Phys. Sin. 58 5624 (in Chinese) [关丽, 李强, 赵庆勋, 郭建新, 周阳, 金利涛, 耿波, 刘保亭 2009 物理学报 58 5624]
[23] Wen P, Li C F, Zhao Y, Zhang F C, Tong L H 2014 Acta Phys. Sin. 63 197101 (in Chinese) [文平, 李春福, 赵毅, 张凤春, 童丽华 2014 物理学报 63 197101]
[24] Ru Q, Li Y L, Hu S J, Peng W, Zhang Z W 2012 Acta Phys. Sin. 61 038210 (in Chinese) [汝强, 李燕玲, 胡社军, 彭薇, 张志文 2012 物理学报 61 038210]
[25] Duan M Y, Xu M, Zhou H P, Shen Y B, Chen Q Y, Ding Y C, Zhu W J 2007 Acta Phys. Sin. 56 5359 (in Chinese) [段满益, 徐明, 周海平, 沈益斌, 陈青云, 丁迎春, 祝文军 2007 物理学报 56 5359]
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