TM@Cu12N12团簇磁性的第一性原理研究

First-principles study of magnetism of TM@Cu12N12 nanoclusters

采用密度泛函理论下的广义梯度近似方法对团簇TM@Cu12N12 (TM=Mn,, Fe, Co, Ni, Cu, Ru, Rh, Pd,Ir, Pt)的结构稳定性、磁性及磁各向异性能进行了系统的理论研究.发现由于TM-Cu和Cu-N键的出现,不同过渡金属原子(TM)掺杂二十面体Cu13N12(ICO)团簇的中心原子可以有效提高TM@Cu12N12的稳定性;N原子的加入使Cu团簇的磁性显著提高,且不同的TM掺杂有效改善了Cu团簇内部的磁性环境;3d原子的掺杂使团簇的磁性得到进一步提升, 4d, 5d原子的掺杂虽对提高团簇轨道磁矩无明显效果,但Rh和Pt原子的掺入使其磁各向异性能显著增大,提高了团簇的磁稳定性.结果表明对TM@Cu12N12的掺杂改性基本可以达到磁性调控目的.

The stability of structure, spin, orbital magnetic moment and magnetic anisotropy energy of TM@Cu12N12(TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) are systematically investigated within the framework of the generalized gradient approximation with on-site coulomb repulsion density-functional theory(DFT-GGA+U).In the orbital moment and magnetic anisotropy energy(MAE) computation procedure, the spin-orbit coupling is considered and implemented. In this article, we mainly focus on the structure stability and tunable magnetism of the TM atom(Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) substituting the centre atom of icosahedron(ICO) Cu13N12 cluster, finally disclose the physics origin of the structure stability, change magnetism and larger MAE. The results show that the different TM atom doping makes the ICO structure of Cu13N12 cluster appears a tiny deformation. The stabilities of the clusters are evidently enhanced due to the formation of Cu-N and Cu-TM bond. In addition, the N-capped clusters more prefer to present a larger magnetic moment than the pure Cu13 one. The magnetic environment of clusters is improved to varying degrees by doping different TM(TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) atoms, which endows TM@Cu12N12 clusters with various magnetic properties. For instance, the doping of 3 d atoms further enhances the spin magnetic moment of the clusters, the Mn, Fe and Co atoms replacing the centre atom of the ICO Cu13N12 generate 35, 32 and 33 giant moments, respectively. In light of the doping of 4 d, 5 d transition metal atoms, the orbital moments of the TM@Cu12N12 clusters do not increase evidently, but the MAE remarkably strengthens for the doping of Rh and Pt atoms, the MAE values reach to 15.34 me V/atom and 6.76 me V/atom for Rh@Cu12N12 and Pt@Cu12N12, respectively. The tunable magnetism of TM@Cu12N12 cluster provides promising applications in spintronics.