ABSORPTION OF SURFACE ACOUSTIC-WAVES BY QUANTUM DOTS - DISCRETE SPECTRUM LIMIT

The absorption of surface acoustic waves (SAWs) by an array of quantum dots in which the mean level spacing Delta is larger than the sound f requency w, the temperature T, and the phase breaking rate tau(phi)(-1 ) is considered. The direct and the intra-level (Debye) contributions to the SAW attenuation coefficient Gamma are evaluated, and it is show n that the sensitivity to weak magnetic fields and spin-orbit scatteri ng (''weak localization effects'') is dramatically enhanced as compare d to the case of a continuous spectrum, Delta < tau(phi)(-1). It is ar gued that the non-invasive measurement of Gamma represents a new tool for the investigation of the temperature dependence of the energy rela xation rate, tau(epsilon)(-1), and the phase breaking rate, tau(phi)(- 1), of isolated electronic systems.