Anomalous acoustoelectric effect in La_{0.67}Ca_{0.33}MnO_{3} films

摘要

We have studied acoustoelectric (AE) effect produced by surface acousticwaves (SAW) in a monolithic layered structure, composed of piezodielectricLiNbO_{3} substrate and La_{0.67}Ca_{0.33}MnO_{3} film. The experimentsunexpectedly revealed in the longitudinal AE effect an anomalous contribution,invariant upon reversal of SAW propagation, which coexists with the ordinary(odd in wave vector) effect. The anomalous effect dominates near themetal-insulator transition, while the ordinary effect prevails at high and lowtemperatures. We show that the anomalous effect is caused by strong modulationof the film conductivity produced by the SAW elastic deformations.