The dc current induced by a coherent surface acoustic wave (SAW) of wave vector q in a ballistic channel of length L is calculated. The current contains two contributions, even and odd in q. The even current exists only in a asymmetric channel, when the electron reflection coefficients r1 and r2, at both channel ends, are different. The direction of the even current does not depend on the direction of the SAW propagation, but is reversed upon interchanging r1 and r2. The direction of the odd current is correlated with the direction of the SAW propagation, but is insensitive to the interchange of r1 and r2. It is shown that both contributions to the current are nonzero only when the electron reflection coefficients at the channel ends are energy dependent. The current exhibits geometric oscillations as a function of qL. These oscillations are the hallmark of the coherence of the SAW and are completely washed out when the current is induced by a flux of noncoherent phonons. The results are compared with those obtained previously by different methods and under different assumptions.
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 15 Sep 2000|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics