Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan.
Nanoscale Res Lett. 2013 Jul 3;8(1):307. doi: 10.1186/1556-276X-8-307.
We have performed low-temperature measurements on a gated two-dimensional electron system in which electron-electron (e-e) interactions are insignificant. At low magnetic fields, disorder-driven movement of the crossing of longitudinal and Hall resistivities (ρxx and ρxy) can be observed. Interestingly, by applying different gate voltages, we demonstrate that such a crossing at ρxx ~ ρxy can occur at a magnetic field higher, lower, or equal to the temperature-independent point in ρxx which corresponds to the direct insulator-quantum Hall transition. We explicitly show that ρxx ~ ρxy occurs at the inverse of the classical Drude mobility 1/μD rather than the crossing field corresponding to the insulator-quantum Hall transition. Moreover, we show that the background magnetoresistance can affect the transport properties of our device significantly. Thus, we suggest that great care must be taken when calculating the renormalized mobility caused by e-e interactions.
我们对一个门控二维电子系统进行了低温测量，在该系统中，电子-电子（e-e）相互作用可以忽略不计。在低磁场下，可以观察到纵向和 Hall 电阻率（ρxx 和 ρxy）交叉处由无序驱动的运动。有趣的是，通过施加不同的栅极电压，我们证明这样的 ρxx ~ ρxy 交叉可以发生在磁场高于、低于或等于 ρxx 中与直接绝缘量子霍尔转变对应的温度无关点的情况。我们明确表明，ρxx ~ ρxy 发生在经典 Drude 迁移率 1/μD 的倒数处，而不是与绝缘量子霍尔转变对应的交叉场。此外，我们表明背景磁电阻可以显著影响我们设备的传输特性。因此，我们建议在计算由 e-e 相互作用引起的重整化迁移率时必须非常小心。
