报告题目：Small transition metal clusters on graphene: Stability, magnetic moment, strain, and coadsorption
报告人：Kang Hway Chuan 教授
Department of ChemistryNational University of Singapore
报告时间：2012年5月16日（周三）下午2：00--2：30
报告地点：独墅湖校区907号楼1445报告室
报告简介：
There is currently much interest on the adsorption of various species on graphene. In our work we focus on the adsorption of small transition metal clusters. We are motivated partially by the numerous potential technological advantages of a graphene substrate and partially by the interesting magnetic behavior of transition metal clusters. Our aim is to gain an understanding of the stability and magnetic moments of Fe, Co, Ni, pure and mixed clusters on graphene. We will discuss our work on dimers, trimers, and tetramers. Our results have shown that a novel adsorbate configuration of the mixed FeCo dimer is a promising motif for magnetic storage element at the atomic scale. We will also discuss ongoing work on the effects of co-adsorption and strain in the graphene support upon the adsorbed clusters. For co-adsorption we are investigating the lateral interactions between transition metal addimers, and also between these dimers and hydrogen adatoms. We explored lateral interactions between co-adsorbates on the same side and also on opposite sides of the graphene lattice in order to understand how these adsorbates on opposite sides of the graphene interact. Our results show that the effect of lateral interaction can be large. However, the magnetic moments are not significantly affected by this lateral interaction. These results indicate that while the stability of the addimers increases significantly, the magnetic moments are robust to co-adsorption. We will also discuss the effects of strain upon the adsorption energy and the magnetic moments of Fe, Co, Ni, Pt adatoms and the magnetically interesting FeCo dimer, showing that strain gradually but significantly changes the adsorption energies due to greater overlap between the metal d-orbitals and the pz-orbitals of the graphene carbon. Again the magnetic moment of the adatoms and the FeCo addimer is stable to the strain in the graphene lattice.
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Biodata
Kang Hway Chuan has a BS (Yale University) and a PhD (Caltech), and spent two postdoctoral years at the DOE Ames Lab. He is currently an Associate Professor with the Chemistry Department at the National University of Singapore, and serves as the Deputy Director of the University Scholars Programme at NUS. He is interested in the applications of quantum mechanical and statistical mechanical methods to a broad range of problems, mostly in surface chemistry and physics. His current research interests include:
1) Dynamical interactions in Car-Parrinello molecular dynamic
2) Magnetic, electronic, and chemical properties of transition metal clusters on surfaces
3) Interactions of silane and disilane on silicon-germanium surfaces
4) Surface sputtering: dynamics and pattern formation
分析化学研究所
材料与化学化工学部
2012-5-14
