中国物理B ›› 2023, Vol. 32 ›› Issue (9): 97303-097303.doi: 10.1088/1674-1056/ace61d

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Phase transition in bilayer quantum Hall system with opposite magnetic field

Ke Yang(杨珂)   

  1. Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
  • 收稿日期:2023-05-05 修回日期:2023-07-10 接受日期:2023-07-11 出版日期:2023-08-15 发布日期:2023-09-07
  • 通讯作者: Ke Yang E-mail:yangke@ucas.ac.cn

Phase transition in bilayer quantum Hall system with opposite magnetic field

Ke Yang(杨珂)   

  1. Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
  • Received:2023-05-05 Revised:2023-07-10 Accepted:2023-07-11 Online:2023-08-15 Published:2023-09-07
  • Contact: Ke Yang E-mail:yangke@ucas.ac.cn

摘要: We construct a mapped bilayer quantum Hall system to realize the proposal that two nearly flatbands have opposite Chern numbers. For the C=±1 case, the two Landau levels of the bilayer experience opposite magnetic fields. We consider a mapped bilayer quantum Hall system at total filling νt=1/2+1/2 where the intralayer interaction is repulsive and the interlayer interaction is attractive. We take exact diagonalization (ED) calculations on a torus to study the phase transition when the separation distance d/lB is driven. The critical point at dc/lB = 0.68 is characterized by a collapse of degeneracy and a crossing of energy levels. In the region d/lB<dc/lB, the states of each level are highly degenerate. The pair-correlation function indicates electrons with opposite pseudo-spins are strong correlated at r=0. We find an exciton stripe phase composed of bound pairs. The ferromagnetic ground state is destroyed by the strong effective attractive potential. An electron composite-Fermion (eCF) and a hole composite Fermion (hCF) are tightly bound. In the region d/lB>dc/lB, a crossover from the ddc limit to the large d limit is observed. The electron and hole composite Fermion liquids (CFL) are realized by composite Fermions (CF) which attach opposite fluxes, respectively.

关键词: fractional quantum Hall effect, bilayer quantum Hall system, opposite magnetic field, quantum phase transition

Abstract: We construct a mapped bilayer quantum Hall system to realize the proposal that two nearly flatbands have opposite Chern numbers. For the C=±1 case, the two Landau levels of the bilayer experience opposite magnetic fields. We consider a mapped bilayer quantum Hall system at total filling νt=1/2+1/2 where the intralayer interaction is repulsive and the interlayer interaction is attractive. We take exact diagonalization (ED) calculations on a torus to study the phase transition when the separation distance d/lB is driven. The critical point at dc/lB = 0.68 is characterized by a collapse of degeneracy and a crossing of energy levels. In the region d/lB<dc/lB, the states of each level are highly degenerate. The pair-correlation function indicates electrons with opposite pseudo-spins are strong correlated at r=0. We find an exciton stripe phase composed of bound pairs. The ferromagnetic ground state is destroyed by the strong effective attractive potential. An electron composite-Fermion (eCF) and a hole composite Fermion (hCF) are tightly bound. In the region d/lB>dc/lB, a crossover from the ddc limit to the large d limit is observed. The electron and hole composite Fermion liquids (CFL) are realized by composite Fermions (CF) which attach opposite fluxes, respectively.

Key words: fractional quantum Hall effect, bilayer quantum Hall system, opposite magnetic field, quantum phase transition

中图分类号:  (Quantum Hall effects)

  • 73.43.-f
73.43.Nq (Quantum phase transitions)