物理
物理
물리
2013年
7期
456-467
,共12页
纳米结构石墨烯%介观输运%Anderson强局域化%标度理论%库仑准能隙
納米結構石墨烯%介觀輸運%Anderson彊跼域化%標度理論%庫崙準能隙
납미결구석묵희%개관수운%Anderson강국역화%표도이론%고륜준능극
nanostructured graphene%mesoscopic transport%Anderson strong localization%scaling theory%Coulomb quasigap
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。
Anderson 跼域化是量子波動性導緻的最重要的物理現象之一。Anderson跼域化理論原是對電子體繫提齣的，但是由于電子波動性隻在很小的範圍內(即相位相榦長度內)有效，使得Anderson跼域化的觀測成為一箇難點。在文章中，作者報道瞭在納米結構石墨烯中首次觀測到的二維Anderson彊跼域化現象。更重要的是作者找到瞭使電子相位相榦長度增長至少一箇量級的方法，使得電子的相位可以更容易地被操控。作者用呎吋標度方法得到三組跼域化長度分彆為1.1，2.0和3.4 mm。跼域化長度隨磁場的變化和理論預測符閤得非常好。大呎度介觀電學輸運，錶現為併行于二維變程跳躍電導的另一通道。低溫下(T<25 K)觀測到費米能級附近存在的庫崙準能隙抑製瞭電子與電子間的非彈性散射，從而使得相位相榦長度增長到10 mm。
Anderson 국역화시양자파동성도치적최중요적물리현상지일。Anderson국역화이론원시대전자체계제출적，단시유우전자파동성지재흔소적범위내(즉상위상간장도내)유효，사득Anderson국역화적관측성위일개난점。재문장중，작자보도료재납미결구석묵희중수차관측도적이유Anderson강국역화현상。경중요적시작자조도료사전자상위상간장도증장지소일개량급적방법，사득전자적상위가이경용역지피조공。작자용척촌표도방법득도삼조국역화장도분별위1.1，2.0화3.4 mm。국역화장도수자장적변화화이론예측부합득비상호。대척도개관전학수운，표현위병행우이유변정도약전도적령일통도。저온하(T<25 K)관측도비미능급부근존재적고륜준능극억제료전자여전자간적비탄성산사，종이사득상위상간장도증장도10 mm。
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.
