PbTe量子阱微结构中非局域电阻的消除
Absence of nonlocal resistance in microstructures of PbTe quantum wells
摘要：
我们报告的实验允许设置上限的自旋霍尔效应和边缘通道的PbTe量子阱嵌入PbEuTe屏障之间的电导的大小。我们重新检查以前的数据获得的外延结构的n型PbSe和PbTe，其中明显的非局部效应和可重复的磁阻振荡被found. In这里，我们表明，这些效应所带来的准周期网络的线程位错相邻的BaF $_2$衬底，这会引起一个p型界面层和相关的寄生并联电导。然后，我们提出的调制掺杂的PbTe/（Pb，Eu）Te：Bi异质结的寄生平行电导的影响最小化，并已观察到量子霍尔运输的微观结构上的运输测量结果，在类似的样品，以前。这些结构具有H形几何形状，并且它们被图案化为嵌入在Pb $_{0.92}$ Eu $_{0.08}$ Te势垒之间的12 nm厚的应变PbTe量子阱。该结构具有不同的横向尺寸对应于扩散和弹道电子输运在非等效L谷。对于这些结构没有非局部电阻检测确认PbTe是一个平凡的绝缘体。自旋霍尔角γ的大小估计是小于0.02的PbTe/PbEuTe微结构中的扩散制度。
英文摘要：
We report on experiments allowing to set an upper limit on the magnitude of the spin Hall effect and the conductance by edge channels in quantum wells of PbTe embedded between PbEuTe barriers. We reexamine previous data obtained for epitaxial microstructures of n-type PbSe and PbTe, in which pronounced nonlocal effects and reproducible magnetoresistance oscillations were found. Here we show that these effects are brought about by a quasi-periodic network of threading dislocations adjacent to the BaF$_2$ substrate, which give rise to a p-type interfacial layer and an associated parasitic parallel conductance. We then present results of transport measurements on microstructures of modulation doped PbTe/(Pb,Eu)Te:Bi heterostructures for which the influence of parasitic parallel conductance is minimized, and for which quantum Hall transport had been observed, on similar samples, previously. These structures are of H-shaped geometry and they are patterned of 12 nm thick strained PbTe quantum wells embedded between Pb$_{0.92}$Eu$_{0.08}$Te barriers. The structures have different lateral sizes corresponding to both diffusive and ballistic electron transport in non-equivalent L valleys. For these structures no nonlocal resistance is detected confirming that PbTe is a trivial insulator. The magnitude of spin Hall angle gamma is estimated to be smaller than 0.02 for PbTe/PbEuTe microstructures in the diffusive regime.
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