Electronic transport in sub-micrometric channels at the LaAlO$_{3}$/SrTiO$_{3}$ interface

TL;DR

This study investigates how the electronic transport properties of nanoscale LaAlO$_{3}$/SrTiO$_{3}$ channels change with size, revealing a transition from metallic to insulating behavior at low temperatures, consistent with quantum point contact physics.

Contribution

It compares AFM-written and lithographically patterned nanoscale channels, demonstrating size-dependent transport behavior and the relevance of quantum effects.

Findings

Channels narrower than 100 nm show a metal-insulator crossover at 50 K.

Applying a positive backgate suppresses the insulating upturn.

Experimental data aligns with quantum point contact models.

Abstract

Nanoscale channels realized at the conducting interface between LaAlO$_{3}$ and SrTiO$_{3}$ provide a perfect playground to explore the effect of dimensionality on the electronic properties of complex oxides. Here we compare the electric transport properties of devices realized using the AFM-writing technique and conventional photo-lithography. We find that the lateral size of the conducting paths has a strong effect on their transport behavior at low temperature. We observe a crossover from metallic to insulating regime occurring at about 50 K for channels narrower than 100 nm. The insulating upturn can be suppressed by the application of a positive backgate. We compare the behavior of nanometric constrictions in lithographically patterned channels with the result of model calculations and we conclude that the experimental observations are compatible with the physics of a quantum point contact.