RENORMALIZATION OF ACOUSTIC-PHONON SPECTRUM AND SPACE DISTRIBUTION OFTHE INDUCED CHARGE IN A DOUBLE-LAYER QUANTUM HALL SYSTEM

The frequency renormalization of acoustic phonons interacting with a d ouble-layer composite fermion system is calculated. The space distribu tion of the density of the charge induced by an external electrostatic potential in a double-layer composite fermion system is determined. I t is shown that for a filling factor for which states with the interla yer statistical interaction and without it can be realized, the emerge nce of such an interaction causes a jump in the phase velocity of a fi nite-frequency acoustic phonon and changes the space distribution of t he charge induced by the external potential. These effects can be used for observing a transition in a double-layer electron system under th e conditions of the fractional quantum Hall effect to a new ground sta te upon a decrease in the separation between the layers. (C) 1998 Amer ican Institute of Physics. [S1063-777X(98)01409-1].