【摘要】：由于具有獨(dú)特的性質(zhì),原子厚度的二維磁性材料受到廣泛的關(guān)注。二維半導(dǎo)體材料通常是內(nèi)秉非磁性的,這限制了它們?cè)谧孕娮訉W(xué)上的應(yīng)用,為使其有效地應(yīng)用于自旋電子器件,有必要在這些非磁性材料中引入可調(diào)控的磁性。研究表明,施加應(yīng)力、引入空位缺陷、替代摻雜和吸附等方法均能夠在二維半導(dǎo)體材料中有效地引入磁性。目前,過(guò)渡族金屬原子替代摻雜的方法已被廣泛用于二維半導(dǎo)體的磁性調(diào)控。與Phosphorene類(lèi)似,α相單層Sn S是非磁性半導(dǎo)體,帶隙約為1.38 e V,因此α相單層Sn S有望作為稀磁半導(dǎo)體基底材料應(yīng)用于自旋電子學(xué)。目前,沒(méi)有關(guān)于在α相單層Sn S中引入磁性的相關(guān)報(bào)道。本論文采用基于密度泛函理論的第一性原理計(jì)算的方法,研究了過(guò)渡族金屬元素替代Sn摻雜對(duì)單層Sn S的幾何結(jié)構(gòu)、電子結(jié)構(gòu)和磁性的影響。主要研究?jī)?nèi)容和研究結(jié)果如下:1、對(duì)于V,Cr,Mn,Fe,Co和Ni替代Sn摻雜的單層Sn S,GGA的計(jì)算結(jié)果顯示:Ni摻雜的單層Sn S不具有磁性,而一個(gè)替代摻雜的V,Cr,Mn,Fe和Co原子在單層Sn S中分別產(chǎn)生3μ,4μ,5μ,4μ和3μ的磁矩,磁矩主要由摻雜原子的3d軌道中未配對(duì)的電子所提供,摻雜原子周?chē)廠(chǎng)n和S原子的p軌道也有部分貢獻(xiàn)。Ni摻雜單層Sn S沒(méi)有磁性的原因是在費(fèi)米能附近的能帶具有較強(qiáng)的巡游性。進(jìn)一步的計(jì)算表明兩個(gè)摻雜的Cr原子之間存在長(zhǎng)程的鐵磁耦合。2、對(duì)于V,Cr,Mn,Fe,Co和Ni替代Sn摻雜的單層Sn S,GGA+U的計(jì)算結(jié)果顯示:一個(gè)替代摻雜的V,Cr,Mn,Fe,Co和Ni原子在單層Sn S中分別產(chǎn)生了3μ, 4μ, 5μ, 4μ, 3μ和2μ的磁矩。與GGA的計(jì)算結(jié)果相比,摻雜原子d電子的關(guān)聯(lián)效應(yīng)明顯地增加了V,Cr,Mn,Fe,Co替代摻雜單層Sn S自旋極化態(tài)的穩(wěn)定性,特別是對(duì)Ni替代摻雜的單層Sn S,Ni原子d電子的關(guān)聯(lián)效應(yīng)使其基態(tài)由自旋非極化態(tài)變?yōu)樽孕龢O化態(tài)。另外,3d電子的關(guān)聯(lián)效應(yīng)不僅明顯地增加摻雜原子的磁矩貢獻(xiàn),而且顯著地改變了兩個(gè)摻雜原子之間的磁耦合。這些結(jié)果顯示:關(guān)聯(lián)效應(yīng)對(duì)摻雜原子d軌道的影響是不可忽略的。
[Abstract]:Due to its unique properties, two-dimensional magnetic materials with atomic thickness have received extensive attention. Two-dimensional semiconductor materials are usually intrinsically nonmagnetic, which limits their application in spintronics. In order to effectively apply them to spintronic devices, it is necessary to introduce controllable magnetism into these non-magnetic materials. The results show that magnetic properties can be effectively introduced into two-dimensional semiconductor materials by applying stress, introducing vacancy defects and substituting doping and adsorption. At present, the substitution of transition metal atoms for doping has been widely used in the magnetic regulation of two-dimensional semiconductors. Similar to Phosphorene, 偽 phase monolayer Sn S is a nonmagnetic semiconductor with a band gap of about 1.38eV.Therefore, 偽 phase monolayer Sn S is expected to be used in spintronics as a diluted magnetic semiconductor substrate. At present, there are no reports about the introduction of magnetic properties into 偽-phase monolayer Sn S. In this paper, the influence of transition metal elements instead of Sn doping on the geometric structure, electronic structure and magnetic properties of monolayer Sn S is studied by using the first principle calculation method based on density functional theory (DFT). The main contents and results are as follows: 1. For V, Cr, mn, Fe, Co and Ni instead of Sn-doped monolayer Sn S, the calculation results show that the Ni-doped monolayer Sn S is not magnetic, but a substitute for V, Cr, mn, and so on. The Fe and Co atoms produce 3 渭, 4 渭, 5 渭, 4 渭 and 3 渭 magnetic moments in the monolayer Sn S, respectively. The magnetic moments are mainly provided by the unpaired electrons in the 3D orbitals of the doped atoms. The p-orbitals of the adjacent Sn and S atoms around the doped atoms also contribute partially. The reason that Ni-doped monolayer Sn S has no magnetism is due to the strong touring of the energy bands near the Fermi energy. Further calculation shows that there is a long-range ferromagnetic coupling between the two doped Cr atoms. 2. For V, Cr, mn, Fe, Co and Ni instead of Sn doped monolayer Sn S, the calculation results of GGA U show that a substitution of V, Cr, mn, Cr, mn is obtained. Fe,Co and Ni atoms produce magnetic moments of 3 渭, 4 渭, 5 渭, 4 渭, 3 渭 and 2 渭 in monolayer Sn S, respectively. Compared with the calculated results of GGA, the correlation effect of d electrons of doped atoms significantly increases the stability of spin polarization states of doped monolayer Sn S substituted by Co, Cr, mn, Fe, Co, especially for Ni instead of doped monolayer Sn S. The correlation effect of d-electrons in Ni atom makes the ground state change from spin-non-polarization state to spin-polarization state. In addition, the correlation effect of 3D electrons not only significantly increases the magnetic moment contribution of the doped atoms, but also significantly changes the magnetic coupling between the two doped atoms. These results show that the effect of correlation effect on the d-orbitals of doped atoms is not negligible.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O469

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