Fe原子薄片的磁性:第一性原理计算

使用基于密度泛函理论的第一原理方法,对Fe单层原子薄片在二维正方、二维六角晶格下的电子结构和磁学性质进行了系统研究.结果表明,二维正方、二维六角以及bcc晶格在平衡晶格常数下都具有磁性,其单位原子磁矩分别为2.65,2.54和2.20μ_В.对二维晶格在被压缩和被拉伸时的磁性计算表明,随着晶格的被拉伸,当最近邻原子间距大于4.40时,铁原子间的键合被拉断,体系单位原子的磁矩趋于孤立Fe原子的磁矩4μ_В;随着原子键长的减小,各体系的磁矩 关键词： Fe 原子薄片 磁性 从头计算

First-principles calculations of magnetism of Fe atomic sheet

The electronic and the magnetic properties of Fe single-layered atomic shees separately with two-dimensional square and hexagonal structures are calculated by the first-principles method based on the spin-polarized density functional theory. The calculations show that planar square and hexagonal as well as the bcc structures manifest their magnetisms at their equilibrium lattice constants. The magnetic moments for these structures are 2.65, 2.54 and 2.20μ_В, respectively. The calculated magnetic properties for the elongated and the compressed bond lengths suggest that when the bond is stretched to a length larger than 4.40, the bond should be broken and the magnetic moments of the systems reach the magnetic moment of an independent Fe atom, 4μ_В. When the bond lengths are reduced, the magnetic moments of all the systems studied decrease correspondingly. At the critical bond lengths (1.80 for planar square lattice, and 1.75 for hexagonal lattice), the magnetisms of the two planar lattices disappear. Using the Stoner theory, the change from magnetism to non-magnetism for the lattice compression is elucidated.