碳纳米管中铁和钒原子自旋相关输运的从头算研究
Ab initio study of spin-dependent transport in carbon nanotubes with iron and vanadium adatoms
摘要：
我们提出了一个从头计算研究的自旋相关的运输扶手椅型碳纳米管与过渡金属吸附，铁或钒。我们忽略了管的曲率的影响和模型的周期性边界条件的石墨烯纳米管。采用基于密度泛函理论的非平衡格林函数方法计算了其电子结构和零偏压电导。吸附物的存在导致一个强烈的散射电子的一个自旋类型。的散射被示出是由于耦合的两个扶手椅带状态的金属3d轨道与匹配的对称性，导致法诺共振出现在传输函数的下降。被分散的自旋类型（多数/少数）取决于吸附质，并解释在d-状态填充。使用一个简单的紧束缚模型，然后使用它来调查的依赖性的传输的纳米管的宽度的结果进行定性再现。我们发现，随着管尺寸的增加，透射下降的宽度减小。
英文摘要：
We present an ab initio study of spin dependent transport in armchair carbon nanotubes with transition metal adsorbates, iron or vanadium. We neglect the effect of tube curvature and model the nanotube by graphene with periodic boundary conditions. A density functional theory based nonequilibrium Green's function method is used to compute the electronic structure and zero-bias conductance. The presence of the adsorbate causes a strong scattering of electrons of one spin type only. The scattering is shown to be due to coupling of the two armchair band states to the metal 3d orbitals with matching symmetry causing Fano resonances appearing as dips in the transmission function. The spin type (majority/minority) being scattered depends on the adsorbate and is explained in terms of d-state filling. The results are qualitatively reproduced using a simple tight-binding model, which is then used to investigate the dependence of the transmission on the nanotube width. We find a decrease in the width of the transmission dip as the tube-size increases.
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