Electronic spectral function for a two-dimensional electron system in the fractional quantum Hall regime

A two-dimensional system of interacting electrons is considered in a strong magnetic field in the fractional quantum Hall regime, where the motion of the electrons is restricted to the lowest Landau level in the lowest subband. Starting from a microscopic quantum-field theory we present a calculation of the electronic spectral function A(epsilon) for a Single layer. From the original Coulomb interaction we separate an effective bosonic paa, which is treated exactly by resummation of Feynman diagrams. For the electron Green's function G(tau-tau'), which is closely related to A(epsilon), we derive an approximate formula that goes beyond perturbation theory and is similar to the solution of an independent-boson model. The independent bosons are the collective excitations, mainly magnetorotons. Constructing a bosonic spectral function with the main features of the collective excitations by the single-mode approximation, we obtain a spectral function A(epsilon) with a double-peak structure and a pseudogap at epsilon approximate to mu for low temperatures. From this result we derive the current-voltage characteristic I(V) for the tunneling of electrons between two layers, which shows a tunneling pseudogap for low temperatures and agrees with recent experiments.