Quantized Hall effect and quantum phase transitions in coupled two-layer electron systems.
Quantized Hall effect and quantum phase transitions in coupled two-layer electron systems.
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耦合两层电子系统中的量子化霍尔效应和量子相变。
DOI：
10.1103/physrevb.47.4394
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Xie
中科院分区：
文献类型：
--
作者：
He;Das Sarma S;Xie
我们研究的性质的多体电子态（和它们之间的量子相变）在一个强的外部磁场下的双量子阱结构作为一个函数的材料参数，定义的两层系统，即，各层的厚度，它们之间的分离，限制电子的个人阱势，和它们之间的势垒。受最近两个实验的启发，我们考虑了两种不同的情况，一种是威尔斯之间（几乎）没有量子隧穿，另一种是大量的阱间量子隧穿。我们使用的球形系统有限尺寸精确对角化技术为我们的计算。通过计算我们精确的小系统数值波函数与各种（假设的）解析波函数的重叠，我们评论各种朗道水平填充因子（\ensuremath{\nu}）的不可压缩性的性质。我们研究，特别是细节，\ensuremath{\nu}=1/2的可能性（即，每个孔中的1/4平均占有率），以及，1（即，1/2占有率）不可压缩状态，其中\ensuremath{\nu}是系统的总填充因子。我们还提供了\ensuremath{\nu}=2/3情形的结果。我们的结论，基于我们在计算中使用的现实系统参数，是在最近的实验实现的\ensuremath{\nu}=1/2分数量子霍尔效应，相关的基态是所谓的"331“状态，这是稳定的竞争之间的井内和井间的电子-电子相关。
We study the nature of the many-body electron states (and quantum phase transitions between them) in a double-quantum-well structure under a strong external magnetic field as a function of the materials parameters that define the two-layer system, namely, the thickness of individual layers, the separation between them, the individual well potentials confining the electrons, and the potential barrier between them. Motivated by two recent experiments, we consider two different situations, one with (almost) no quantum tunneling between the wells, and the other with substantial interwell quantum tunneling. We use the spherical system finite-size exact diagonalization technique for our calculations. By calculating the overlap of our exact small-system numerical wave functions with various (postulated) analytic wave functions, we comment on the nature of the incompressibility for various Landau-level filling factors (\ensuremath{\nu}). We investigate, in particular details, the possibility of \ensuremath{\nu}=1/2 (i.e., 1/4 average occupancy in each well), and, 1 (i.e., 1/2 occupancy in each well) incompressible states where \ensuremath{\nu} is the total filling factor for the system. We also provide results for the \ensuremath{\nu}=2/3 situation. Our conclusion, based on our use of realistic system parameters in our calculations, is that in both the recent experimental realizations of the \ensuremath{\nu}=1/2 fractional quantum Hall effect, the relevant ground state is the so-called ``331'' state which is stabilized by the competition between intrawell and interwell electron-electron correlations.