EFFECT OF WAVE-FUNCTION OVERLAP ON THE MAGNETOPLASMONS IN THE FRACTIONAL QUANTUM HALL REGIME

We present a theory for the effect of wave-function overlap on the magnetoplasmons in the fractional quantum Hall regime in a superlattice. We find that there is a competition between the enhancement of the wave-function-overlap effect and the decreases of the long-range parts of both the screened intralayer and interlayer Coulomb interactions. Consequently, when the ratio of the barrier width to the well width is small, there is an instability of the nu = 1/5 Laughlin ground state towards the Wigner crystallization, due to a small collective excitation gap and a comparatively large separation between electrons. The nu = 1/3 Laughlin ground state, on the other hand, shows more stiffness to the collective excitation-gap energy, and the stability of this ground state is mainly determined by the electron density of the system. Therefore, if the electron mobility and the electron density are high enough, we expect to observe the nu = 1/3 fractional quantum Hall effect in the superlattice with wave-function overlap.