Murugesan Ramasamy, Meng Ruishen, de Volder Alexander, Keijers Wout, Janssens Ewald, van de Vondel Joris, Afanasiev Valeri, Houssa Michel
Semiconductor Physics Laboratory, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
J Phys Condens Matter. 2022 Aug 1;34(40). doi: 10.1088/1361-648X/ac829e.
The interaction between Au(= 1-6) clusters and graphene is studied using first-principles simulations, based on density functional theory. The computed binding energy between Auand graphene depends on the number of atoms in the cluster and lies between -0.6 eV and -1.7 eV, suggesting (weak) chemisorption of the clusters on graphene, rather than physisorption. Overall, the electronic properties, spin-orbit interaction and spin texture, as well as the transport properties of graphene strongly depend on the precise size of the Auclusters. Doping of graphene is predicted for clusters with an odd number of Au atoms, due to overlap between Auand carbonstates close to the Fermi level. On the other hand, there is no charge transfer between even size Au clusters and graphene, but a gap is formed at the Dirac cone, due to the breaking of the pseudo spin inversion symmetry of graphene's lattice. The adsorbed Auclusters induce spin-orbit interactions as well as spin and pseudo spin interactions in graphene, as indicated by the splitting of the electronic band structure. A hedgehog spin texture is also predicted for adsorbed clusters with an even number of Au atoms. Ballistic transport simulations are performed to study the influence of the adsorbed clusters on graphene's electronic transport properties. The influence of the cluster on the electron transmission across the structure depends on the mixing of the valence orbitals in the transport energy window. In the specific case of the Au/graphene system, the adsorbed clusters reduce the transmission and the conductance of graphene. The Auclusters act as 'scattering centers' for charge carriers, in agreement with recent experimental studies.
基于密度泛函理论，利用第一性原理模拟研究了Au(= 1 - 6)团簇与石墨烯之间的相互作用。计算得到的Au与石墨烯之间的结合能取决于团簇中的原子数，介于-0.6 eV和-1.7 eV之间，这表明团簇在石墨烯上发生了（弱）化学吸附，而非物理吸附。总体而言，石墨烯的电子性质、自旋轨道相互作用和自旋纹理以及输运性质强烈依赖于Au团簇的精确尺寸。对于具有奇数个Au原子的团簇，预计会发生石墨烯的掺杂，这是由于靠近费米能级的Au和碳态之间存在重叠。另一方面，偶数尺寸的Au团簇与石墨烯之间没有电荷转移，但由于石墨烯晶格的赝自旋反转对称性被破坏，在狄拉克锥处形成了一个能隙。吸附的Au团簇在石墨烯中诱导出自旋轨道相互作用以及自旋和赝自旋相互作用，这由电子能带结构的分裂表明。对于具有偶数个Au原子的吸附团簇，还预测了一种刺猬状自旋纹理。进行了弹道输运模拟以研究吸附团簇对石墨烯电子输运性质的影响。团簇对电子穿过该结构的传输的影响取决于传输能量窗口中价轨道的混合情况。在Au/石墨烯系统的特定情况下，吸附的团簇降低了石墨烯的传输和电导。Au团簇充当电荷载流子的“散射中心”，这与最近的实验研究一致。
