Instituto de Física da Universidade de São Paulo, 135960-170, São Paulo, SP, Brazil.
Phys Rev Lett. 2010 Apr 23;104(16):166401. doi: 10.1103/PhysRevLett.104.166401. Epub 2010 Apr 20.
We study the transport properties of HgTe-based quantum wells containing simultaneously electrons and holes in a magnetic field B. At the charge neutrality point (CNP) with nearly equal electron and hole densities, the resistance is found to increase very strongly with B while the Hall resistivity turns to zero. This behavior results in a wide plateau in the Hall conductivity sigma(xy) approximately = 0 and in a minimum of diagonal conductivity sigma(xx) at nu = nu(p) - nu(n) = 0, where nu(n) and nu(p) are the electron and hole Landau level filling factors. We suggest that the transport at the CNP point is determined by electron-hole "snake states" propagating along the nu = 0 lines. Our observations are qualitatively similar to the quantum Hall effect in graphene as well as to the transport in a random magnetic field with a zero mean value.
我们研究了同时含有电子和空穴的 HgTe 基量子阱在磁场 B 中的输运性质。在电荷中性点 (CNP) 处，电子和空穴密度几乎相等，此时电阻随 B 的增加而强烈增大，而霍尔电阻率变为零。这种行为导致霍尔电导率 σ(xy)约等于 0 的宽平台和对角电导率 σ(xx)在 ν = ν(p) - ν(n) = 0 时的最小值，其中 ν(n) 和 ν(p) 分别为空穴和电子朗道能级填充因子。我们提出，在 CNP 点处的输运由沿 ν = 0 线传播的电子-空穴“蛇态”决定。我们的观察结果与石墨烯中的量子霍尔效应以及具有零平均值的随机磁场中的输运定性相似。
