铁磁接触石墨烯中自旋相关电子输运的理论研究
Theoretical studies of spin-dependent electronic transport in ferromagnetically contacted graphene flakes
摘要:
基于紧束缚模型和递归格林函数技术,研究了微小石墨烯片(片)中自旋相关的弹道输运。主要的兴趣集中在:电导率,巨磁电阻(GMR)和散粒噪声。结果表明,当石墨烯片夹在两个铁磁电极之间时,所得的GMR系数可能是相当显着的。这种说法适用于锯齿形和扶手椅手性,以及不同的纵横比(宽度/长度)。值得注意的是,在绝对值上,扶手椅边缘石墨烯薄片的GMR系统地大于对应于扶手椅边缘石墨烯薄片的GMR。这一发现是由于不同程度的导电通道混合的两个手性的问题。它还表明,对于大的纵横比薄片,三维端部接触的引线,非常像侵入性接触,导致电导率和Fano因子的非通用行为。
英文摘要:
Based on a tight-binding model and a recursive Green's function technique, spin-depentent ballistic transport through tinny graphene sheets (flakes) is studied. The main interest is focussed on: electrical conductivity, giant magnetoresistance (GMR) and shot noise. It is shown that when graphene flakes are sandwiched between two ferromagnetic electrodes, the resulting GMR coefficient may be quite significant. This statement holds true both for zigzag and armchair chiralities, as well as for different aspect (width/length) ratios. Remarkably, in absolute values the GMR of the armchair-edge graphene flakes is systematically greater than that corresponding to the zigzag-edge graphene flakes. This finding is attributed to the different degree of conduction channel mixing for the two chiralities in question. It is also shown that for big aspect ratio flakes, 3-dimensional end-contacted leads, very much like invasive contacts, result in non-universal behavior of both conductivity and Fano factor.
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