Excitation Spectrum and Effective Mass of the Even-Fraction Quantum Hall Liquid

摘要: To probe the nature of even-fraction quantum Hall system, we have investigated low-lying excitation spectrum by exact diagonalization for finite systems. We found (i) a striking one-to-one correspondence (i.e., shell structure) between and those free (composite) fermions, (ii) surprisingly straight scaling plot energy that gives zero gap (metal) in thermodynamic limit, (iii) effective mass evaluated from becoming heavier nu = 1/2,1/4,1/6, but (iv) some deviations single-mode or Hartree-Fock composite fermion approximation.