Half-metallic graphene nanodots: A comprehensive first-principles theoretical study
Half-metallic graphene nanodots: A comprehensive first-principles theoretical study
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DOI：
10.1103/physrevb.77.035411
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发表时间：
2008-01-01
影响因子：
3.7
通讯作者：
Scuseria, Gustavo E.
中科院分区：
文献类型：
--
作者：
Hod, Oded;Barone, Veronica;Scuseria, Gustavo E.
对有限矩形石墨烯纳米带的电子特性和半金属性质进行了全面的第一性原理理论研究。我们确定 C28H14 分子的双蒽异构体是呈现自旋极化基态的最小石墨烯衍生物。即使在这个量子点水平上，预计自旋也会在系统的两个锯齿形边缘处反铁磁性地排列。根据经验，我们发现，如果系统宽度为 1 nm 或更宽，则至少三个连续单位长的锯齿形石墨烯边缘将呈现自旋极化。预测具有 1 nm 及更长之字形边缘的带材的磁排序的室温可检测性。对于研究的较长系统，自旋波结构出现在一些高自旋多重态中。观察到能隙振荡随锯齿形边缘的长度变化。发现这些振荡的幅度小于无限带的预测幅度。研究发现，即使对于有限且极短的系统，带在外部面内电场下的半金属性质也得以保留。
A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of finite rectangular graphene nanoribbons is presented. We identify the bisanthrene isomer of the C28H14 molecule to be the smallest graphene derivative to present a spin-polarized ground state. Even at this quantum dot level, the spins are predicted to be aligned antiferromagnetically at the two zigzag edges of the system. As a rule of thumb, we find that zigzag graphene edges that are at least three consecutive units long will present spin polarization if the width of the system is 1 nm or wider. Room temperature detectability of the magnetic ordering is predicted for ribbons with zigzag edges 1 nm and longer. For the longer systems studied, spin wave structures appear in some high spin multiplicity states. Energy gap oscillations with the length of the zigzag edge are observed. The amplitude of these oscillations is found to be smaller than that predicted for infinite ribbons. The half-metallic nature of the ribbons under an external in-plane electric field is found to be preserved even for finite and extremely short systems.