《mn掺杂limgp新型稀磁半导体的光电性质》由会员分享，可在线阅读，更多相关《mn掺杂limgp新型稀磁半导体的光电性质（13页珍藏版）》请在金锄头文库上搜索。
1、Mn 掺杂 LiMgP 新型稀磁半导体的光电性质 陈婷 庞军 何红 彭赟 吴楠 徐建 杜成旭 庞星星 毋志民 崔玉亭 重庆师范大学物理与电子工程学院光电功能材料重庆市重点实验室 摘 要： 采用基于密度泛函理论的第一性原理平面波超软赝势法, 对新型稀磁半导体Li1y (Mg1-xMnx) P (x=0, 0.125;y=0, 0.125) 体系进行几何结构优化, 计算并对比分析了体系的电子结构、形成能、电荷重叠布局、差分电荷密度及光学性质.结果表明, LiMgP 体系中化学键均表现为极化的共价键, 磁性元素 Mn 的掺入形成了强于 Mg-P 的 Mn-P 共价键, 且产生自旋极化杂质带, 通过改
2、变 Li 的计量数可以改变体系的性质和参与杂化的轨道.与单掺 Mn 相比, Li 过量体系表现为金属性, 杂质带宽度增大, 而净磁矩减小, 同时形成能降低, 导电能力增强, Mn-P 键的相互作用减弱;Li 空位体系表现为半金属性, 半金属能隙为0.478 eV, 净磁矩为 4.02 , Mn-P 键的重叠电荷布局数最大, 键长最小, Mn和 P 原子之间的电子云最密集且共用电子对偏移程度最小, Mn3d 和 P3p 间杂化作用最强.通过对比体系光学性质发现, Mn 掺入后介电函数和光吸收谱在低能区出现新的峰值, 同时复折射率函数也发生明显变化, 体系扩大了对电磁波的吸收范围, 能量损失明显减
3、小.关键词： Mn 掺杂 LiMgP; 电子结构; 电荷重叠布局; 差分电荷密度; 光学性质; 作者简介：毋志民, E-mail:收稿日期：2017-05-04基金：重庆市基础与前沿研究计划 (cstc2014jcyj A50005) Photoelectric properties of Mn-doped LiMgP new diluted magnetic semiconductorCHEN Ting PANG Jun HE Hong PENG Yun WU Nan XU Jian DU ChengXu PANG XingXing WU ZhiMin CUI YuTing Chongqin
4、g Key Laboratory of Photoelectric Functional Materials, College of Physics and Electronic Engineering, Chongqing Normal University; Abstract： We optimized the geometry structures of Li1y (Mg1-xMnx) P for (x=0.125; y=0, 0.125) by adopting the first-principles calculation of plane wave ultra-soft pseu
5、do-potential technology based upon the density function theory (DFT) . Then we calculated the electronic structures, formation energies, electric density difference and optical properties. The results reveal that spin polarization impurity bands were produced in Mn doped system. The properties of sy
6、stem and the orbits of participate in hybridization could be changed by dominating the amount of Li. The Mn doped system still revealed semiconductor properties, and the width of impurity band is 0.461 eV, and the magnetic moment is 4.98 . The Li overdose system revealed metallicity, and the width o
7、f impurity bands increased to 0.890 eV, and the magnetic moment decreased to 4.10 . Meanwhile the total energies and the formation energies reduced, the conductive capability increased. The Li deficient system revealed half metallicity, and the half-metallic band gap is 0.478 eV, and the magnetic mo
8、ment is 4.02 . Most of the charge overlap populations of LiMgP system are positive. It means all the chemical bonds of LiMgP are covalent bonds. Magnetism element Mn doped into the system creates Mn-P covalent bonds that are stronger than Mg-P bonds. In the Mn doped system, the quantity of share ele
9、ctron increased and the deviation of share electron decreased. The charge overlap population of Li-P bond is -0.02 which reveals ionic bonds. In the Li overdose system, the charge overlap population of Mn-P bonds reach the minimum value of 0.52. The density of states of Mn3d and P3p at the Fermi lev
10、el is larger than that of single doped Mn, but at the same time, the interaction of the Mn-P bonds is weakened due to the participation of Li2s in orbital hybridization. Formation energy and total energy become lower. And in the Li deficient system, the charge overlap population of Mn-P bonds reache
11、d the maximum value of 0.69, and the bonds lengths reached the minimum value. The electron cloud of Mn atoms and P atoms is the densest, and the deviation of the share electron is the weakest. The results reveal that p-d hybridization happened in Mn3d and P3p, and the hybridization was the strongest
12、. The deficiency of the electron cloud of P atoms of charge density difference was caused by the deficiency of Li atoms. Analyzing images of optical properties can find that the imaginary part of dielectric function and the optical spectroscopy appeared a new peak at low energy region in Mn doped sy
13、stem. And the complex refractive index functions have a significant change at the same time. It means the system has an augment optical absorption range, and energy loss get lower.Keyword： Mn-doped LiMgP; electronic structure; overlapping charge distribution; electron density difference; optical pro
14、perties; Received： 2017-05-04在现代信息技术中, 对信息的处理主要是利用半导体电子的电荷自由度, 对信息的存储则是利用磁性材料电子的自旋自由度, 设计出具有能耗低、运行速率快、体积小等优点的新型自旋电子器件, 将有望突破 Moor 定律的瓶颈.而稀磁半导体 (diluted magnetic semiconductor, DMS) 正是向研发工艺成熟的半导体中掺入过渡族金属或稀土金属元素以实现自旋注入, 从而将电子的电荷自由度和自旋自由度集于同一基体, 使其同时具备磁性材料和半导体材料的性质.但是, 传统的稀磁半导体中载流子和磁矩均由同一掺杂元素提供, 这种自旋与电
15、荷的捆绑效应严重制约了材料电性和磁性的调控维度, 并且基于 III-V 族 DMS的不等价代替还会导致磁性离子化学固溶度严重受限, Mn 的平均固溶度不足 l%, 仅可形成亚稳态薄膜材料4, 材料的质量严重依赖于制备方法并对热处理过程有较高的敏感性5.为解决上述难题, Maek 等人6和 Deng 等人7通过理论和实验发现了一类新型的 I-II-V 族基 Li1y (Zn1-xMnx) As 新型稀磁半导体, 在 Zn 位注入 Mn 只引入了自旋, 载流子浓度则可通过改变 Li 的含量来进行调控, 这样就可以实现自旋和电荷注入机制的分离.研究发现当掺入 3%的 Mn 时, 即可拥有接近 3 的
16、饱和磁矩, 且材料具有低的矫顽力 (30 Oe) , 这为瞄准应用的低场调控自旋和电荷提供了可能, 但遗憾的是 Li (Zn, Mn) As 的居里温度 (Tc) 只有 50 K, 远低于室温的要求7.Sato 等人8利用 Korringa-Kohn-Rostoker 方法的相干近似理论计算了 Mn 掺 Li Zn As, Li Zn P, Li Zn N 体系的电子结构, 结果表明 Li 空位能够有效地抑制体系的亚稳态分解, 诱导 Mn 离子间的铁磁交换作用, 提高体系的 Tc.Deng 等人9发现 Li (Zn, Mn) P 为较小矫顽力的软磁性材料, 可以通过电荷和自旋分离掺杂的方法合成, 并通过增加载流子浓度提高 Tc.Wang 等人10通过实验发现当 Cr 掺杂浓度为 10%时, Li 1.1 (Zn1-xCrx) As 的 Tc达到了 218 K.Yu 等人11和 Djeroud 等人12对 Li Mg P的研究表明, 根据间隙插
