Quantum oscillations in the surface-acoustic-wave attenuation caused by a two-dimensional electron system.

The interaction of surface acoustic ~aves with a two-dimensional electron system is investigated on GaAs/Ga~ „Al„As heterojunctions at low temperatures ( T 4.2 K) and high magnetic fields ( ~ 10 T). Surface acoustic waves are propagated through the heterojunction containing a highmobility two-dimensional electron gas and situated between the emitting and receiving transducers. The interaction between the two-dimensional electron system and the surface acoustic wave produces strong quantum oscillations in the sound attenuation and the sound velocity which can be quantitatively explained.