Acoustoelectric charge transport at the LaAlO3/SrTiO3 interface

Y. Uzun, A. E.M. Smink, M. P. De Jong*, H. Hilgenkamp, W. G. Van Der Wiel

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

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.

Original languageEnglish
Article number011601
JournalApplied physics letters
Volume116
Issue number1
Early online date3 Jan 2020
DOIs
Publication statusPublished - 6 Jan 2020

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