The two-dimensional electron system (2DES) formed at the interface of LaAlO3 (LAO) and SrTiO3 (STO), both band insulators in bulk, exhibits properties not easily attainable in conventional electronic materials. The extreme shallowness of the 2DES, only a few nanometers below the surface, opens up unique possibilities such as tunneling spectroscopy, local electronic sensing, and in situ patterning by manipulating the surface properties. It is particularly tempting to manipulate the charge carriers with surface acoustic wave (SAW) phonons, which are confined to the surface. However, the absence of intrinsic piezoelectricity in both LAO and STO complicates the electric generation of SAWs, as well as the induction of an acoustoelectric current. Here, we present robust acoustoelectric coupling between SAWs and the LAO/STO 2DES by using electrostriction in STO, induced by a dc electric field. Electromechanical coupling to the carriers is provided by phonon-induced modulation of the 2DES potential well, leading to SAW-induced carrier transport. The ability to control charge carriers with SAWs brings the versatile LAO/STO 2DES into reach of quantum acoustics, opening possibilities to study the interplay of nanoscale mechanical waves and the rich physics exhibited by nonpiezoelectric complex oxides, including superconductivity, magnetism, and correlated insulator states.

中文翻译：

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LaAlO3/SrTiO3界面的声电荷传输

在 LaAlO3 (LAO) 和 SrTiO3 (STO) 的界面处形成的二维电子系统 (2DES)，这两种带绝缘体都是块状的，表现出传统电子材料不易获得的特性。2DES 的极浅度（仅在表面以下几纳米）开辟了独特的可能性，例如隧道光谱、局部电子传感和通过操纵表面特性的原位图案化。用表面声波 (SAW) 声子操纵电荷载流子特别诱人，这些声子被限制在表面。然而，LAO 和 STO 都缺乏固有的压电性，使 SAW 的发电以及声电流的感应复杂化。这里，我们通过在 STO 中使用由直流电场感应的电致伸缩，在 SAW 和 LAO/STO 2DES 之间提出了强大的声电耦合。与载流子的机电耦合由声子诱导的 2DES 势阱调制提供，导致 SAW 诱导的载流子传输。使用 SAW 控制电荷载流子的能力将多功能 LAO/STO 2DES 带入量子声学领域，为研究纳米级机械波与非压电复合氧化物（包括超导性、磁性和相关绝缘体状态）所展示的丰富物理学之间的相互作用开辟了可能性.