LOW-FREQUENCY PHONON ABSORPTION BY A MAGNETICALLY QUANTIZED 2D ELECTRON-SYSTEM

The rate of absorption of phonons from a monochromatic beam by a 2D el ectron system in a strong magnetic field is calculated in the diffusiv e regime and it is seen that, for certain phonon frequencies, the vari ation of absorption with Fermi energy should have two maxima per Landa u level with a separation which scales as square-root B. This calculat ion is extended into the lower-temperature, quantum Hall regime using a scaling expression for the diffusion constant showing that the phono n absorption should vanish as the temperature is lowered in the same m anner as the longitudinal conductivity.