Nature of the CFL–FL phase transition in periodically modulated Landau levels

Determine the nature of the direct phase transition between the composite Fermi liquid and the Fermi liquid that is suggested by the Drude-weight data as the ratio of periodic potential strength to Coulomb interaction V0/U0 is varied in the lowest Landau level with a periodic potential, using finite-size studies and appropriate scaling analyses to characterize the transition.

Background

The paper studies interacting electrons projected to the lowest Landau level subject to a periodic potential, which serves as a minimal Chern band model. Exact diagonalization reveals a regime with a composite Fermi liquid (CFL) at small V0/U0 and a Fermi liquid (FL) at larger V0/U0, sharply distinguished by their Drude weight: vanishing in CFL and finite in FL.

The numerical Drude weight as a function of V0/U0 suggests a direct transition between CFL and FL. However, establishing the precise character of this transition (e.g., the type of criticality and scaling) from finite-size systems requires careful analysis beyond the scope of the present work.