摘要:
Anderson 局域化是量子波动性导致的最重要的物理现象之一。Anderson局域化理论原是对电子体系提出的，但是由于电子波动性只在很小的范围内(即相位相干长度内)有效，使得Anderson局域化的观测成为一个难点。在文章中，作者报道了在纳米结构石墨烯中首次观测到的二维Anderson强局域化现象。更重要的是作者找到了使电子相位相干长度增长至少一个量级的方法，使得电子的相位可以更容易地被操控。作者用尺寸标度方法得到三组局域化长度分别为1.1，2.0和3.4 mm。局域化长度随磁场的变化和理论预测符合得非常好。大尺度介观电学输运，表现为并行于二维变程跳跃电导的另一通道。低温下(T<25 K)观测到费米能级附近存在的库仑准能隙抑制了电子与电子间的非弹性散射，从而使得相位相干长度增长到10 mm。
Abstract:
Anderson localization is one of the most important physical phenomena caused by the wave nature of quantum particles. It was originally proposed for the electronic system,but never clearly observed because the wave nature of electrons is usually only manifest at extremely small dis-tances,denoted the dephasing length,and therefore making the observation very difficult. In this arti-cle we report the first observation of Anderson localization in 2 dimensions,on nanostructured gra-phene. Perhaps more important is the fact that we have discovered a way to enhance the dephasing length of electrons,by at least one order of magnitude,so that the electron phase may now be more easi-ly manipulated. In this article,we use exponential sample-size scaling of conductance to demonstrate strong electron localization in three sets of nanostructured antidot graphene samples with localization lengths of 1.1,2.0,and 3.4 μm. The localization length is observed to increase with applied magnetic field,in accurate agreement with the theoretical prediction. The large-scale mesoscopic transport is manifest as a parallel conduction channel to 2D variable range hopping,with a Coulomb quasigap around the Fermi level. The opening of the correlation quasigap,observable below 25 K through the temperature dependence of conductance,makes possible the exponential suppression of inelastic scat-terings and thereby leads to an observed dephasing length of 10 μm.
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