Grauer S, Fijalkowski K M, Schreyeck S, Winnerlein M, Brunner K, Thomale R, Gould C, Molenkamp L W
Faculty for Physics and Astronomy (EP3 and TP1), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Phys Rev Lett. 2017 Jun 16;118(24):246801. doi: 10.1103/PhysRevLett.118.246801.
We report on the scaling behavior of V-doped (Bi,Sb){2}Te{3} samples in the quantum anomalous Hall regime for samples of various thickness. While previous quantum anomalous Hall measurements showed the same scaling as expected from a two-dimensional integer quantum Hall state, we observe a dimensional crossover to three spatial dimensions as a function of layer thickness. In the limit of a sufficiently thick layer, we find scaling behavior matching the flow diagram of two parallel conducting topological surface states of a three-dimensional topological insulator each featuring a fractional shift of 1/2e^{2}/h in the flow diagram Hall conductivity, while we recover the expected integer quantum Hall behavior for thinner layers. This constitutes the observation of a distinct type of quantum anomalous Hall effect, resulting from 1/2e^{2}/h Hall conductance quantization of three-dimensional topological insulator surface states, in an experiment which does not require decomposition of the signal to separate the contribution of two surfaces. This provides a possible experimental link between quantum Hall physics and axion electrodynamics.
我们报告了不同厚度的V掺杂（Bi，Sb）₂Te₃样品在量子反常霍尔 regime 下的标度行为。虽然先前的量子反常霍尔测量显示出与二维整数量子霍尔态预期相同的标度，但我们观察到随着层厚度的变化，出现了向三个空间维度的维度交叉。在足够厚的层的极限情况下，我们发现标度行为与三维拓扑绝缘体的两个平行导电拓扑表面态的流图相匹配，每个表面态在流图霍尔电导率中具有1/2e²/h的分数偏移，而对于较薄的层，我们恢复了预期的整数量子霍尔行为。这构成了对一种独特类型的量子反常霍尔效应的观测，该效应源于三维拓扑绝缘体表面态的1/2e²/h霍尔电导量子化，且该实验不需要分解信号来分离两个表面的贡献。这为量子霍尔物理和轴子电动力学之间提供了一个可能的实验联系。
