Dynamical Signatures of Edge-State Magnetism on Graphene Nanoribbons
Dynamical Signatures of Edge-State Magnetism on Graphene Nanoribbons
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DOI：
10.1103/physrevlett.106.226401
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发表时间：
2011-05-31
影响因子：
8.6
通讯作者：
Honecker, Andreas
中科院分区：
文献类型：
--
作者：
Feldner, Helene;Meng, Zi Yang;Honecker, Andreas
我们使用投影量子蒙特卡罗模拟和自洽平均场近似的Hubbard模型研究了石墨烯纳米带的边缘态磁性。静态磁关联被发现是短期的。然而，相关长度增加的宽度的带状物，这样已经为中等宽度的带状物，我们观察到一个强烈的趋势，平均场型铁磁相关性在锯齿形边缘。这些相关性是伴随着一个占主导地位的低能量峰值在本地的光谱功能，我们建议，这可以用来检测边缘状态的磁性扫描隧道显微镜。动态自旋结构因子在边缘的一个带表现出近似线性分散集体类磁振子模式在低能量衰减成斯通纳模式超出的能量尺度，它合并到粒子-空穴连续。
We investigate the edge-state magnetism of graphene nanoribbons using projective quantum Monte Carlo simulations and a self-consistent mean-field approximation of the Hubbard model. The static magnetic correlations are found to be short ranged. Nevertheless, the correlation length increases with the width of the ribbon such that already for ribbons of moderate widths we observe a strong trend towards mean-field-type ferromagnetic correlations at a zigzag edge. These correlations are accompanied by a dominant low-energy peak in the local spectral function and we propose that this can be used to detect edge-state magnetism by scanning tunneling microscopy. The dynamic spin structure factor at the edge of a ribbon exhibits an approximately linearly dispersing collective magnonlike mode at low energies that decays into Stoner modes beyond the energy scale where it merges into the particle-hole continuum.