Mikhailov Sergey A
Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany.
Nanomaterials (Basel). 2024 Jan 31;14(3):297. doi: 10.3390/nano14030297.
The fractional quantum Hall effect was experimentally discovered in 1982. It was observed that the Hall conductivity σyx of a two-dimensional electron system is quantized, σyx=e2/3h, in the vicinity of the Landau level filling factor ν=1/3. In 1983, Laughlin proposed a trial many-body wave function, which he claimed described a "new state of matter"-a homogeneous incompressible liquid with fractionally charged quasiparticles. Here, I develop an exact diagonalization theory that allows one to calculate the energy and other physical properties of the ground and excited states of a system of two-dimensional Coulomb interacting electrons in a strong magnetic field. I analyze the energies, electron densities, and other physical properties of the systems with N≤7 electrons continuously as a function of magnetic field in the range 1/4≲ν<1. The results show that both the ground and excited states of the system resemble a sliding Wigner crystal whose parameters are influenced by the magnetic field. Energy gaps in the many-particle spectra appear and disappear as the magnetic field changes. I also calculate the physical properties of the ν=1/3 Laughlin state for N≤8 and compare the results with the exact ones. This comparison, as well as an analysis of some other statements published in the literature, show that the Laughlin state and its fractionally charged excitations do not describe the physical reality, neither at small nor in the thermodynamic limit. The results obtained shed new light on the nature of the ground and excited states in the fractional quantum Hall effect.
分数量子霍尔效应于1982年被实验发现。人们观察到,在朗道能级填充因子ν = 1/3附近,二维电子系统的霍尔电导率σyx是量子化的,即σyx = e²/3h。1983年,劳克林提出了一个试探性的多体波函数,他声称该函数描述了一种“新的物质状态”——一种具有分数电荷准粒子的均匀不可压缩液体。在这里,我发展了一种精确对角化理论,该理论能让人们计算强磁场中二维库仑相互作用电子系统基态和激发态的能量及其他物理性质。我连续分析了N≤7个电子的系统在1/4≲ν<1范围内作为磁场函数的能量、电子密度和其他物理性质。结果表明,系统的基态和激发态都类似于一种滑动的维格纳晶体,其参数受磁场影响。随着磁场变化,多粒子能谱中的能隙会出现和消失。我还计算了N≤8时ν = 1/3劳克林态的物理性质,并将结果与精确值进行比较。这种比较以及对文献中其他一些论述的分析表明,劳克林态及其分数电荷激发在小尺寸和热力学极限下都不能描述物理现实。所得到的结果为分数量子霍尔效应中基态和激发态的本质提供了新的见解。