Fermi liquid effects and quasiparticle mass renormalization in a system of two-dimensional electrons with strong interaction

The dependence of the quasiparticle Fermi energy on the electron density is investigated by analyzing the radiative recombination spectra of two-dimensional electrons with photoexcited holes bound at remote acceptors. In this way, the electron-density dependence of the renormalized mass of quasiparticles is determined. It is established that, as the electron density decreases (the parameter $r_s$ increases to 4.5), the density-of-states effective mass of quasiparticles increases by 35% as compared to the cyclotron mass of the electron. It is shown that, in a perpendicular magnetic field, the concept of quasiparticles in a two-dimensional Fermi liquid is applicable not only near the Fermi level but also deeply below the Fermi surface, even to the bottom of the quantum-confinement subband, because the broadening of excitations remains considerably smaller than their energy.