首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
         下载免费PDF全文
韩瑞林  姜世民  闫羽 《中国物理 B》2017,26(2):27502-027502
In this paper, the magnetic properties, electronic structures and the stabilities of Zn/Cd incorporated two-dimensional Al N nanosheets are investigated by the first-principles method. Numerical results indicate that Zn and Cd substituting Al atom in Al N nanosheets introduce some holes into the 2p orbitals of the N atoms, and the holes mainly come from spindown 2p orbitals of the N atoms. The magnetic moment of 1.0 μBis produced by Zn/Cd doping Al N nanosheets, and the main component of the magnetic moment of the system is contributed by the partially filled 2p states of the N atoms around the dopant. In particular, when Zn/Cd substituting Al atoms, the magnetic coupling is found to be ferromagnetic. We attribute the hole-mediated p–d interaction to the created ferromagnetic coupling. More importantly, the result of formation energy indicates that Al atom is more inclined to be replaced by Zn atom rather than Cd. This finding is beneficial to developing the spin electronic devices.  相似文献   

2.
采用基于密度泛函理论(DFT)的平面波超软赝势法,研究了Cu、Ag、Au掺杂AlN的晶格常数、磁矩、能带结构和态密度。电子结构表明,Cu、Ag、Au的掺杂使在带隙中引入了由杂质原子的d态与近邻N原子的2p态杂化而成的杂质带,都为p型掺杂,增强了体系的导电性。Cu掺杂AlN具有半金属铁磁性,半金属能隙为0.442eV,理论上可实现100%的自旋载流子注入;Ag掺杂AlN具有很弱的半金属铁磁性;而Au掺杂AlN不具有半金属铁磁性。因此,与Ag、Au相比,Cu更适合用来制作AlN基稀磁半导体。  相似文献   

3.
采用基于密度泛函理论的平面波超软赝势和广义梯度近似的第一性原理计算方法,对理想纤锌矿AlN及不同浓度的Cu掺AlN的超晶胞结构进行了几何优化,计算并分析了它们的电子结构、磁电性质和光学性质.结果表明,掺杂后Cu3d态电子与其近邻的N2p态电子发生杂化,在带隙中引入杂质带,6.25%和12.5%的Cu掺杂体系表现出半金属铁磁性,体系总磁矩分别为2.56μв和2.42μв,25%的Cu掺杂体系表现出金属性.随着Cu浓度的增加,体系铁磁性反而减弱.Cu掺杂后体系介电函数虚部和复折射率函数在低能区发生明显变化,增强了体系对低频电磁波的吸收.当Cu浓度增加时体系对高频电磁波的吸收也随之加强.  相似文献   

4.
利用基于密度泛函理论的平面波超软赝势法研究了N空位对Cu掺杂AlN的电子结构和磁学性质的影响。结果表明,与Cu最近邻的N原子更易失去形成N空位。N空位的引入减小了Cu掺杂AlN体系的半金属能隙;减弱了Cu及其近邻N原子的自旋极化的强度以及Cu3d与N2p轨道间的杂化,因而减小了体系的半金属铁磁性。因此,制备Cu掺杂AlN稀磁半导体时应尽可能地避免产生N空位。  相似文献   

5.
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Ag掺杂AlN 32原子超晶胞体系进行几何结构优化,计算并分析体系的电子结构、磁性和光学性质.结果表明:Ag掺杂后,Ag4d态电子与其近邻的N2p态电子发生杂化,引入杂质带形成受主能级,实现p型掺杂,使体系的导电能力增强,同时表现出金属性和弱磁性,其净磁矩为1.38μв.掺杂形成的N-Ag键电荷集居数较小,表现出强的离子键性质.掺杂后体系的介电函数虚部和光吸收谱在低能区出现新的峰值,同时复折射率函数在低能区发生变化,吸收边向低能方向延展,体系对长波吸收加强,能量损失明显减小.  相似文献   

6.
毕艳军  郭志友  林竹  董玉成 《发光学报》2008,29(6):1031-1035
基于密度泛函理论(DFT)的总体能量平面波超软赝势方法,结合广义梯度近似(GGA),对Co单独掺杂ZnO和(Co,Mn)共掺杂ZnO的32原子超原胞体系进行了几何结构优化,计算了纤锌矿结构ZnO、Co-ZnO及(Co,Mn)共掺杂ZnO的能带结构、电子态密度,并对此进行了详细的分析.计算结果表明,ZnO中单独掺杂Co元素显示出铁磁性行为,Mn的引入减弱了Co-ZnO的铁磁性.  相似文献   

7.
The electronic structures and magnetic properties of(Mn, N)-codoped Zn O are investigated by using the firstprinciples calculations. In the ferromagnetic state, as N substitutes for the intermediate O atom of the nearest neighboring Mn ions, about 0.5 electron per Mn^2+ion transfers to the N^2-ion, which leads to the high-state Mn ions(close to +2.5)and trivalent N3-ions. In an antiferromagnetic state, one electron transfers to the N2-ion from the downspin Mn2+ion,while no electron transfer occurs for the upspin Mn^2+ion. The(Mn, N)-codoped Zn O system shows ferromagnetism,which is attributed to the hybridization between Mn 3d and N 2p orbitals.  相似文献   

8.
         下载免费PDF全文
The stability and electronic structures of AlN nanowires with and without N-vacancy are investigated using firstprinciples calculations.We find that there is an inverse correlation between formation energy and diameter in ideal AlN nanowires.After calculating the formation energies of N-vacancy at different sites in AlN nanowires with different diameters,we find that the N-vacancy prefers to stay at the surface of the nanowires and it is easier to fabricate them under Al-rich conditions.Through studying the electronic properties of AlN nanowires with N-vacancies,we further find that there are two isolated bands in the deep part of the band gap,one of them is fully occupied and the other is half occupied.The charge density indicates that the half-fully occupied band arises from the Al at the surface,and this atom becomes an active centre.  相似文献   

9.
         下载免费PDF全文
董珊  朱峰 《中国物理 B》2012,21(9):97502-097502
We report on the electron-mediated ferromagnetism in Fe-doped InP from both first-principles calculations and experiments. Theoretically, based on the spin-polarized density functional theory within the Heyd-Scuseria-Ernzerhof (HSE03) approach, we systematically investigate the magnetic properties of Fe-doped InP and predict the existence of electron-mediated ferromagnetism. Experimentally, by diffusing Fe into the n-type InP wafer with thermal annealing at 800 C, we observe room-temperature ferromagnetism in InP:Fe, which is in agreement with the theoretical prediction.  相似文献   

10.
We perform a first-principles study of electronic structure and magnetism of C-doped zinc-blende ZnO using the full-potential linearized augmented plane wave method. Results show that C-doped zinc-blende ZnO exhibits half-metallic ferromagnetism with a stable ferromagnetic ground state. The calculated magnetic moment of the 32-atom supercell containing one C dopant is 2.00 μ B , and the C dopant contributes most. The calculated low formation energy suggests that C-doped zinc-blende ZnO is energetically stable. The hole-mediated double exchange mechanism can be used to explain the ferromagnetism in C-doped zinc-blende ZnO.  相似文献   

11.
曹萍  白越  赵东旭  申德振 《发光学报》2011,32(4):383-386
通过电化学沉积方法成功生长了Co掺杂ZnO的薄膜,但并没有实现室温下的铁磁性.通过NH3等离子体的后处理,导致有一部分N原子进入了ZnO晶格替代了一部分O格位,从而在ZnO中产生空穴.在空穴间接交换作用下,ZnCoO薄膜中产生了被束缚的磁极子,产生了室温下的铁磁性.  相似文献   

12.
运用第一性原理的全势能线性缀加平面波方法对闪锌矿结构CrSe和CrAs的电子结构进行自旋极化计算。闪锌矿结构CrSe和CrAs处于晶格平衡时都具有半金属性,它们自旋向下的电子能带带隙分别为3.38eV 和1. 79eV,同时,它们的自旋总磁矩分别为4.00和3.00μB/formula。自旋总磁矩主要来源于Cr的原子磁矩,Se和As的原子磁矩对总磁矩的贡献很小而且为负值,因而它们具有明显的铁磁性特征. 使晶体晶格在±10%的范围内发生各向同性形变,对闪锌矿结构CrSe和CrAs的电子结构进行计算. 计算结果表明,当晶格各向同性形变分别为-4 % ~ 10 %和-2 % ~10 %时,闪锌矿结构CrSe和CrAs仍然保持半金属铁磁性,并且总磁矩都稳定于4.00和3.00μB/formula.  相似文献   

13.
袁娣  黄多辉  罗华锋 《物理学报》2012,61(14):147101-147101
基于密度泛函理论框架下的第一性原理平面波超软赝势方法,研究了掺杂和非掺杂AlN体系的晶格参数、 能带结构、总体态密度、分波态密度、差分电荷分布及电荷集居数.计算结果表明: Be掺杂AlN晶体能够在能隙中形成深受主能级,空穴载流子局域于价带顶, 而引入了激活施主O原子的Be, O共掺杂方法,能使受主能带变宽、非局域化特征明显. 同时,受主能级向低能方向移动,形成了浅受主能级, 从而提高了Be原子的掺杂浓度和系统的稳定性. Be, O共掺杂更有利于获得p型AlN.  相似文献   

14.
Using a first-principle method, the electronic structures and the impurity formation energy of ZnO, ZnO (N), ZnO (N+B), and ZnO (2N+B) have been calculated, based on which the feasibility to obtain p-type ZnO & discussed. According to the results, when ZnO is single doped by N, the acceptor level is deep, and the formation energy is negative, so the ideal p-type ZnO can not be obtained by this way. On the contrary, when 2N+B are codoped into ZnO, the acceptor level becomes much lower, and the formation energy is positive, so it is a better way to obtain p-type ZnO.  相似文献   

15.
运用第一性原理的全势能线性缀加平面波方法对闪锌矿结构CrSe和CrAs的电子结构进行自旋极化计算.闪锌矿结构CrSe和CrAs处于晶格平衡时都具有半金属性,它们自旋向下的电子能带带隙分别为3.38 eV和1.79 eV,同时,它们的自旋总磁矩分别为4.00和3.00μ_B/formula.自旋总磁矩主要来源于Cr的原子磁矩,Se和As的原子磁矩对总磁矩的贡献很小而且为负值,因而它们具有明显的铁磁性特征.使晶体晶格在±10%的范围内发生各向同性形变,对闪锌矿结构CrSe和CrAs的电子结构进行计算.计算结果表明,当晶格各向同性形变分别为-4%~10%和-2%~10%时,闪锌矿结构CrSe和CrAs仍然保持半金属铁磁性,并且总磁矩都稳定于4.00和3.00μ_B/formula.  相似文献   

16.
采用基于密度泛函理论的局域自旋密度近似加U法(LSDA+U:Hubbard参数)计算了多铁材料BiFeO3铁电相以及稀土元素Gd掺杂BiFeO3材料的能带结构、态密度(DOS)、原子轨道占据数和净电荷分布等,对稀土元素Gd掺杂BiFeO3可能引起的电子结构、介电常数和铁磁性的改变进行了第一性原理研究。计算结果表明:Gd掺杂对材料钙钛矿结构影响不大,BiFeO3铁电性主要来源于Fe原子3d轨道和O原子2p轨道杂化;掺杂Gd后材料中的Fe原子和O原子的共价性减弱,Bi原子和O原子的离子性增强,禁带宽度变窄,绝缘性减弱,铁磁性明显增强;计算得到的光学性质表明材料的静态介电常数有所增加。  相似文献   

17.
姚仲瑜  孙丽  潘孟美  孙书娟  刘汉军 《物理学报》2018,67(21):217501-217501
构建只含有一种过渡金属元素的half-Heusler合金VLiBi和CrLiBi.采用第一性原理的全势能线性缀加平面波方法计算half-Heusler合金VLiBi和CrLiBi的电子结构.计算结果表明,VLiBi和CrLiBi是半金属性铁磁体,它们的半金属隙分别是0.25 eV和0.46 eV,晶胞总磁矩分别为3.00 μB和4.00 μB.磁性计算结果显示,晶胞总磁矩主要来源于V和Cr的原子磁矩,Li和Bi的原子磁矩较弱,而且Bi的原子磁矩为负值.利用平均场近似方法计算合金的居里温度TC,VLiBi和CrLiBi的居里温度(TC)的估算值分别为1401 K和1551 K.使晶格常数在±10%的范围内变化,分别计算VLiBi和CrLiBi的电子结构.计算研究表明,晶格常数在-5.6%–10%和-6.9%–10%的范围内变化时VLiBi和CrLiBi仍具有半金属性,并且晶胞总磁矩稳定于3.00 μB和4.00 μB.采用局域密度近似(LDA)+U(电子库仑相互作用项)的方法计算VLiBi和CrLiBi的电子结构,当U的取值增大到5 eV时VLiBi和CrLiBi仍保持半金属性.此外,采用考虑自旋-轨道耦合(spin-orbit coupling,SOC)效应的广义梯度近似(GGA)+SOC方法计算VLiBi和CrLiBi的电子结构,计算结果显示有微弱的自旋向下能带穿过费米能级,此时VLiBi和CrLiBi在费米面处的自旋极化率分别为98.8%和94.3%,它们的晶胞总磁矩分别为3.03 μB和4.04 μB.VLiBi的半金属性几乎不受SOC效应的影响,而CrLiBi在费米面处仍有较高的自旋极化率.  相似文献   

18.
First-principles calculations based on spin density functional theory are performed to study the spin-resolved electronic properties of ZnO codoped with Cu and N. (Cu, N)-codoped ZnO exhibits magnetism, and the total magnetic moment mainly originates from the p-d hybridization of Cu-N and Cu-O as well as p-p coupling interaction between N and O at the Fermi level. The Zn34Cu2O35N1 favors energetically a ferromagnetic ground state due to the existence of stable Cu-N-Cu complex. These results imply that the (Cu, N)-codoped ZnO is a promising dilute magnetic semiconductor free of magnetic precipitates, which could broaden the horizon of currently known magnetic systems.  相似文献   

19.
采用基于密度泛函理论的局域自旋密度近似加U法(LSDA+U:Hubbard参数)计算了多铁材料BiFeO3铁电相以及稀土元素Gd掺杂BiFeO3材料的能带结构、态密度(DOS)、原子轨道占据数和净电荷分布等,对稀土元素Gd掺杂BiFeO3可能引起的电子结构、介电常数和铁磁性的改变进行了第一性原理研究。计算结果表明:Gd掺杂对材料钙钛矿结构影响不大,BiFeO3铁电性主要来源于Fe原子3d轨道和O原子2p轨道杂化;掺杂Gd后材料中的Fe原子和O原子的共价性减弱,Bi原子和O原子的离子性增强,禁带宽度变窄,绝缘性减弱,铁磁性明显增强;计算得到的光学性质表明材料的静态介电常数有所增加。  相似文献   

20.
稀土元素(Y,La)掺杂ZnO的电子结构和光学性质   总被引:1,自引:0,他引:1  
吴玉喜  胡智向  顾书林  渠立成  李腾  张昊 《物理学报》2011,60(1):17101-017101
采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算了未掺杂ZnO和稀土(Y,La)掺杂ZnO体系的空间结构、能带、电子态密度与光学性质.结果表明,掺杂后体系的形成能减小,稳定性变强,带隙展宽,费米能级进入导带中,体系呈金属性,载流子发生简并,形成简并半导体.定性分析了掺杂后光学性质的变化.关键词:氧化锌掺杂第一性原理  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号