文档介绍：摘要本文利用紧束缚近似模型和格林函数方法研究了基于石墨烯的铁磁体/石墨烯纳米带/铁磁体结构中的电子输运性质。我们分别研究了散射区域为完美和收缩的锯齿型、扶手型石墨烯纳米带的隧穿磁电阻、与自旋相关的电导和自旋极化,结果表明: 当完美锯齿型石墨烯纳米带宽度N为偶数时,与自旋相关的电导均出现零电导平台,在铁磁电极的磁化方向反平行时零电导平台更宽。在费米能零点附近出现100%隧穿磁电阻平台和100%(一100%)自旋极化平台。当散射区域发生收缩后,电导受到抑制而隧穿磁电阻和自旋极化在费米能(,)区域外均有不同程度的增大,同时自旋极化在费米能零点附近出现翻转。当完美锯齿型石墨烯纳米带宽度N为奇数时,对于铁磁电极的磁化方向反平行情况,电导存在零电导平台;在铁磁电极的磁化方向平行情况下,。当散射区域发生收缩后,铁磁电极的磁化方向反平行时,零电导平台没有发生变化;而铁磁电极的磁化方向平行时,电导在费米能零点附近振荡消失,同时收缩使电导在一些费米能区域增大或者减小。隧穿磁电阻在费米能零点附近出现100%平台且平台的宽度不随着收缩发生变化,自旋极化值并没有发生太大变化。当完美扶手型石墨烯纳米带宽度N=3m(柳为整数)时,收缩会使电导变小且零电导平台加宽,而100%隧穿磁电阻平台会随着收缩变宽,自旋极化100%(一100%)平台的宽度也会随着收缩变宽。当完美扶手型石墨烯纳米带宽度N=3m+2时,收缩使电导除个别小区域外基本为零,而收缩却使隧穿磁电阻由60%提升Nloo%,%%,即收缩使自旋极化和隧穿磁电阻得到加强。关键词:石墨烯电导隧穿磁电阻自旋极化 Inthispaper,we investigated theelectronic transport property through agrapheme—based ic/grapheme nanoribbon(GNR)/icjunction by using the Green’S function technique and Landauer-BtRtiker calculated theconductance, oresistance and spinpolarization inthefollowing scatteringregion:perfect and contractivezigzag grapheme nanoribbon(ZGNR),perfect and contractive armchairgrapheme nanoribbon(AGNR),respectively. Itisfound thatthespin—dependent conductance emerges zero conductance plateau when N(the witdhoftheperfectzigzaggraphene nanoribbon)is even,and theconductance has a wider zero conductance plateau in the antiparallel 00% oresistance(MR)plateau andthe 100%(一100%)spin polarization plateau emerges around zero Fermi the scattering region has a contraction,the conductance is suppressed,however,the value oftheMR andthespin polarization isenhanced when the Fermi energy outside theregion of(-,),meanwhile,an inversionappears around zero Fermi energy. The conductance intheantiparaUelconfigurations shows zero conductance plateau and the conductance intheparallel configurations isalways large than when Nisodd. The zero conductance plateau intheantiparallel configurations remains tobeunchanged when thescatteringregion ha