First-principles study of substitutional metal impurities in graphene: structural, electronic and magnetic properties
First-principles study of substitutional metal impurities in graphene: structural, electronic and magnetic properties
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DOI：
10.1088/1367-2630/12/5/053012
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发表时间：
2009-10
影响因子：
3.3
通讯作者：
E. Santos;A. Ayuela;D. Sánchez-Portal
中科院分区：
文献类型：
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作者：
E. Santos;A. Ayuela;D. Sánchez-Portal
我们提出了一个理论研究，使用密度泛函计算的结构，电子和磁性的3d过渡金属，贵金属和锌原子与石墨烯中的碳单空位相互作用。我们特别注意这些替代杂质的电子和磁性，并发现它们可以完全理解使用一个简单的模型的基础上的状态之间的杂交的金属原子，特别是d壳，和与未重构的D3h碳空位的缺陷水平。我们确定了三种不同的区域与不同的碳-金属杂化电子能级的占据相关：（i）Sc和Ti的成键态被完全填充，这些杂质是非磁性的;（ii）V，Cr和Mn的非成键d壳层被部分占据，相应地，这些杂质呈现大的和局域的自旋矩;（iii）Co、Ni、贵金属和Zn的反键态随着碳特征的增加而逐渐被填充。这些杂质的自旋磁矩在0和1 μ B之间振荡，并且越来越离域。取代Zn遭受来自C3v对称性的Jahn-Teller样畸变，因此具有零自旋矩。Fe在制度（ii）和（iii）之间的边界处占据独特的位置，并显示出更复杂的行为：虽然它在广义梯度近似（GGA）计算的水平上是非磁性的，但它的自旋矩可以使用GGA + U计算以适度的U参数值打开。
We present a theoretical study using density functional calculations of the structural, electronic and magnetic properties of 3d transition metal, noble metal and Zn atoms interacting with carbon monovacancies in graphene. We pay special attention to the electronic and magnetic properties of these substitutional impurities and find that they can be fully understood using a simple model based on the hybridization between the states of the metal atom, particularly the d shell, and the defect levels associated with an unreconstructed D3h carbon vacancy. We identify three different regimes associated with the occupation of different carbon–metal hybridized electronic levels: (i) bonding states are completely filled for Sc and Ti, and these impurities are non-magnetic; (ii) the non-bonding d shell is partially occupied for V, Cr and Mn and, correspondingly, these impurities present large and localized spin moments; (iii) antibonding states with increasing carbon character are progressively filled for Co, Ni, the noble metals and Zn. The spin moments of these impurities oscillate between 0 and 1μB and are increasingly delocalized. The substitutional Zn suffers a Jahn–Teller-like distortion from the C3v symmetry and, as a consequence, has a zero spin moment. Fe occupies a distinct position at the border between regimes (ii) and (iii) and shows a more complex behavior: while it is non-magnetic at the level of generalized gradient approximation (GGA) calculations, its spin moment can be switched on using GGA+U calculations with moderate values of the U parameter.