Quantum magnetotransport of a periodically modulated two-dimensional electron gas.
Quantum magnetotransport of a periodically modulated two-dimensional electron gas.
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周期性调制二维电子气的量子磁输运。
DOI：
10.1103/physrevb.49.1827
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Tan
中科院分区：
文献类型：
--
作者：
Tan
研究了二维电子在周期势场中的磁电阻效应。一维调制使朗道能级展宽，二维调制使朗道能级进一步分裂为类霍夫施塔特谱。最近观察到的韦斯振荡表明加宽的朗道能级的振荡带宽，其中最小值出现在一维调制的平带条件（零带宽）。然而，平坦带似乎给出二维调制的最大值。在本文中，电导率的一维和二维调制已得到解析。结果表明，能带分裂增强了散射电导率的降低，而能带电导率则显著降低。因此，当朗道能级从平带加宽时，散射电导率的降低比带电导率的增加更快。因此，总电导率在平坦带处显示出最大值，与一维情况相反。此外，还利用无网格数方法进行了数值研究。一个显着的差异之间观察到的一维和二维调制。这可以用与频带分裂的结果相同的方式来解释。
The magnetoresistance of two-dimensional electrons in a periodic potential is studied. The Landau levels are broadened by one-dimensional modulation, and are further split into a Hofstadter-like spectrum by two-dimensional modulation. The recently observed Weiss oscillation manifests the oscillatory bandwidth of broadened Landau levels, where the minima appear at the flat-band condition (zero bandwidth) for one-dimensional modulation. However the flat bands seem to give the maxima for two-dimensional modulation. In this paper, the conductivity for both one-and two-dimensional modulations has been obtained analytically. It is shown that the decrease of the scattering conductivity is enhanced by the band splitting, while the band conductivity is reduced significantly. Consequently, the scattering conductivity decreases faster than the increase of the band conductivity as the Landau level is broadened from the flat band. Therefore the total conductivity shows maximum at flat bands, in contrast to the one-dimensional case. Moreover a numerical study has been made by using the Thouless number method. A dramatic difference is observed between one-and two-dimensional modulations. This can be explained in the same way as the result of band splitting.