Single Layer Control of Nanoscale Metal-Insulator Transition at the LaAlO₃/SrTiO₃ Interface.

Abstract

Modern quantum device fabrication often requires precisely adding and removing materials <i>in situ</i> at nanoscales, which is challenging for high-quality correlated oxide devices. In this work, we present a novel nanofabrication method that remotely controls the interfacial metal-insulator transition at the LaAlO₃/SrTiO₃ interface by selectively removing an LaAlO₃ overlayer using a diamond tip. Remarkably, we observe a large force window within which single atomic layer precision of control is achievable. Our results confirm the critical thickness and charge transfer mechanism through a layer-by-layer removal process at the interface. Additionally, high-quality nanodevices, including nanochannels and single electron transistors, are successfully fabricated using this method. This nonvolatile and high-precision nanofabrication method provides a promising oxide platform for quantum engineering by harnessing the rich electron correlations at the nanoscale.