The size dependence of the magnetic edge states in zigzag graphene nanoflakes (GNFs) with different aspect ratios is studied using density functional theory. The results show that GNFs smaller than a certain critical size exhibit a closed‐shell nonmagnetic ground state, whereas at the critical size or larger, the nanoflakes have an open‐shell antiferromagnetic (AFM) ground state with a spin density localized along the edges. The formation of a spin‐collinear domain wall beyond the critical size, where the AFM order emerges, was analyzed, finding that this transition is a result of multiple symmetry breakings of highest singly occupied molecular orbitals (SOMO and SOMO‐1). The collinear domain wall is strongly dependent on the perpendicular distance between parallel edges. Furthermore, it is found that the formation of the collinear domain wall in zigzag GNFs is associated with the behavior of the bond‐length alternation at the edges.

中文翻译：

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石墨烯纳米薄片边缘的自旋共线畴壁的形成

使用密度泛函理论研究了不同纵横比的之字形石墨烯纳米薄片（GNF）中磁性边缘态的尺寸依赖性。结果表明，小于特定临界尺寸的GNF呈现闭壳非磁性基态，而在临界尺寸或更大时，纳米片具有开壳反铁磁（AFM）基态，其自旋密度沿边缘分布。分析了超出临界尺寸的自旋共线畴壁的形成，在该尺寸处出现了AFM阶，发现这种转变是由最高单个占据的分子轨道（SOMO和SOMO-1）多次对称破裂造成的。共线畴壁在很大程度上取决于平行边缘之间的垂直距离。此外，