Unified explanation of acoustoelectric current in charge-density-wave materials

Develop theoretical models that consistently explain the experimentally observed temperature dependence and surface-acoustic-wave propagation-direction dependence of the acoustoelectric current in charge-density-wave materials.

Background

The paper investigates acoustoelectric currents generated by surface acoustic waves in NbSe3 and 2H-TaSe2, both of which undergo charge-density-wave transitions. The measurements reveal temperature-dependent enhancement and polarity reversal of the current near the charge-density-wave transitions, as well as a reversal of current polarity when the surface-acoustic-wave propagation direction on the LiNbO3 substrate is rotated by 90 degrees.

The authors compare these observations with several existing theoretical descriptions of dc current generation by acoustic waves. They report that the available models do not simultaneously account for all of the observed temperature and propagation-direction dependences. Although the paper proposes a phenomenological strain-modulated-conductivity model that qualitatively captures key features, it does not provide a complete theoretical explanation, leaving the formulation of a consistently successful model as an unresolved problem.