Department of Physics, Southeast University, Nanjing, People's Republic of China.
J Phys Condens Matter. 2010 Nov 10;22(44):445801. doi: 10.1088/0953-8984/22/44/445801. Epub 2010 Oct 22.
We study electron spin resonance in zigzag graphene nanoribbons by applying a rotating magnetic field on the system without any bias. By using the nonequilibrium Green's function technique, the spin-resolved pumped current is explicitly derived in a rotating reference frame. The pumped spin current density increases with the system size and the intensity of the transverse rotating magnetic field. For graphene nanoribbons with an even number of zigzag chains, there is a nonzero pumped charge current in addition to the pumped spin current owing to the broken spatial inversion symmetry of the system, but its magnitude is much smaller than the spin current. The short-ranged static disorder from either impurities or defects in the ribbon can depress the spin current greatly due to the localization effect, whereas the long-ranged disorder from charge impurities can avoid inter-valley scattering so that the spin current can survive in the strong disorder for the single-energy mode.
我们通过在系统上施加旋转磁场来研究无偏置情况下锯齿形石墨烯纳米带中的电子自旋共振。通过使用非平衡格林函数技术，我们在旋转参考系中明确推导出了自旋分辨泵送电流。泵送自旋电流密度随系统尺寸和横向旋转磁场强度的增加而增加。对于具有偶数个锯齿链的石墨烯纳米带，由于系统的空间反演对称性被破坏，除了泵送自旋电流之外，还有非零的泵送电荷电流，但由于其大小远小于自旋电流。由于局域化效应，来自带中的杂质或缺陷的短程静态无序会大大抑制自旋电流，而来自电荷杂质的长程无序可以避免谷间散射，从而使得自旋电流在单能模式下的强无序中得以存活。
