Acoustoelectric charge transport at the LaAlO₃/SrTiO₃ interface by surface acoustic waves

Surface acoustic waves (SAWs) are capable of transporting free charge carriers along their propagation path, resulting in an acoustoelectric current or voltage. This has been explored intensively in AlGaAs/GaAs heterostructures. Here, we integrate SAWs with the LaAlO₃/SrTiO₃ 2-dimensional electron system, which is known to exhibit high mobility at low temperature, magnetism and superconductivity under the appropriate conditions. Despite the non-piezoelectric nature of SrTiO₃ (and LAO) we can make use electrostriction for SAW generation. We measure the acoustoelectric effect both at room temperature and at 150 K, and observe a considerable enhancement at lower temperatures. Our results suggest robust coupling between the SAWs and the interfacial free electrons, which opens the way for applying the same approach in other non-piezoelectric (complex-oxide) systems.