ConAl (n= 1–8)合金团簇结构和磁性质研究

采用密度泛函理论中的广义梯度近似(DFT-GGA)对Co_nAl (n= 1–8)合金团簇进行了系统的几何、 电子结构和磁性质研究. 研究结果表明Al原子倾向于与Co原子形成最大的成键数, 即Al原子均处在团簇原子拥有最大配位数的位置上. Al掺杂后Co_nAl团簇的稳定性减弱, 磁性降低. 磁性降低的幅度与实验上对较大Co_nAl_M团簇的磁性检测结果获得了很好地符合. 在所有Co_nAl团簇的最稳定结构中, 除Co₄Al外, Al与近邻Co原子均呈现反铁磁性耦合. 相对于纯Co团簇,非磁性Al元素的掺入以及Al掺杂后Co原子整体自旋极化的减弱 是导致Co_nAl团簇磁性的降低主要原因. 关键词： nAl合金团簇')" href="#">Co_nAl合金团簇 几何结构 磁性 自旋极化

Structural, electronic and magnetic properties of ConAl (n= 1–8) clusters

Based on DFT-GGA calculations, we systematically investigate the structures, electronic and magnetic properties of Co_nAl (n= 1–8) clusters. The results indicate that the aluminum prefers to maximize the number of Co-Al bonds by selecting the site which increases the coordination of cobalt atoms with Al. The doped Al makes the stability of Co_nAl clusters weakened and the magnetism decreased as compared with that of Co_n+1 clusters. The reduction magnitude of magnetism of the doping Al accords well with recent Stern-Gerlach experimental result for larger Co_nAl_M clusters. In all of the Co_nAl alloy clusters, the Al atom is found to be aligned antiferromagnetically with its neighbor Co atoms except for Co₄Al. As compared with the magnetism of pure Co cluster, the magnetism of Co_nAl cluster is reduced, which is attributed mainly to nor-magnetism Al element embeding and the weakening of spin polarization of the Co atoms.