title: Excitation spectrum and effective mass of the even-fraction quantum hall liquid
abstract: To probe the nature of the even-fraction quantum Hall system, we have investigated the low-lying excitation spectrum by exact diagonalization for finite systems. We have found (i) a striking one-to-one correspondence (i.e., a shell structure) between the spectrum and those for free (composite) fermions, (ii) a surprisingly straight scaling plot for the excitation energy that gives a zero gap (metal) in the thermodynamic limit, (iii) the effective mass evaluated from the scaling becoming heavier for nu = 1/2,1/4,1/6, but (iv) some deviations from the single-mode or the Hartree-Fock composite fermion approximation.
authors.affiliation: High Energy Accelerator Research Organization (KEK), Tanashi Branch, Tokyo 188-8501, Japan.
authors.initials: M
authors.lastname: Onoda
authors.initials: T
authors.lastname: Mizusaki
authors.initials: T
authors.lastname: Otsuka
authors.initials: H
authors.lastname: Aoki