On the absence of higher generations of incompressible daughter states of composite Fermion quasiparticles

18th International Conference on Recent Progress in Many-Body Theories

Quinn, John J.^1

University of Tennessee, Knoxville

TN

37996, United States^1

关键词: Applied magnetic fields;    Electron filling factors;    Interaction energies;    Laughlin quasielectrons;    Low-energy excitations;    Quantum Hall systems;    Quantum phase transitions;    Spin-polarized system;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/702/1/012006/pdf
DOI  :  10.1088/1742-6596/702/1/012006

来源: IOP

【 摘 要 】

Jain [1] introduced a simple mean-field (MF) composite Fermion (CF) picture by attaching to each electron in a quantum Hall system a flux tube producing a Chern- Simons magnetic field b(r) = 2pφ0Σiδ(r - ri). Here φ0= hc/e is the quantum of flux, and the sum is over all electron coordinates ri. He then averaged the total flux and the total charge (electronic plus positive background) over the entire sample. This MF picture gave a system of noninteracting CFs in an effective magnetic field B∗0= νB0. It predicted incompressible quantum liquid (IQL) states at filling factors ν = n(1 + 2pn)-1for integral values of n. Chen and Quinn [2] demonstrated that Jain's MF CF picture predicted the total angular momentum values of the lowest energy band of states for any value of the applied magnetic field B0. Justification of when the MFCF picture was valid was given by Wojs and Quinn [3], who extended the CF hierarchy scheme of Sitko et al. [4]. The CF hierarchy gave the Jain states for integrally filled CF Landau levels (CF LLs), and the Haldane hierarchy of all odd denominator fractions when quasiparticles in the highest (partially filled) CF angular momentum shell had interactions sufficiently similar to the Coulomb interactions of electrons in the lowest Landau level. Sitko et al. showed that the predictions of the CF hierarchy scheme were not always correct. By using a simple pair angular momentum identity and the concept of fractional grandparentage, Wojs and Quinn showed that higher generations of CFs could result from the interactions of the original CF quasiparticles only if their interaction energy VQP(L2) as a function of their pair angular momentum L2increased with increasing L2faster than L2(L2+ 1). For Laughlin quasielectrons of the ν = 1/3 IQL state this condition was not satisfied. Therefore, no second generation of CFs could occur. The observed IQL at electron filling factor ν = 4/11 can not be attributed to a daughter IQL state at νQE= 1/3 in a totally spin polarized system. Rather, it is an IQL state of electron pairs with pair angular momentum ιp= 2ι - 1. A description of the IQL state of electron pairs and its low energy excitations will be presented, and the possibility of a spin flip quantum phase transition as a function of well width and applied magnetic field will be discussed.