Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3 Interface

TL;DR

This study investigates anomalous transport phenomena in quasi-one-dimensional LaAlO3/SrTiO3 nanostructures, revealing large nonlocal resistances and suppression by superconductivity, suggesting complex underlying physics involving spin-orbit coupling and magnetic interactions.

Contribution

It demonstrates the creation of narrow LaAlO3/SrTiO3 structures via atomic force microscope lithography and reports novel nonlocal transport behaviors in these quasi-1D systems.

Findings

Large nonlocal resistances observed in some structures

Suppression of nonlocal transport below superconducting transition

Resistance comparable to quantum resistance h/e2

Abstract

The oxide heterostructure LaAlO3/SrTiO3 supports a two-dimensional electron liquid with a variety of competing phases including magnetism, superconductivity and weak antilocalization due to Rashba spin-orbit coupling. Further confinement of this 2D electron liquid to the quasi-one-dimensional regime can provide insight into the underlying physics of this system and reveal new behavior. Here we describe magnetotransport experiments on narrow LaAlO3/SrTiO3 structures created by a conductive atomic force microscope lithography technique. Four-terminal local transport measurements on ~10-nm-wide Hall bar structures yield longitudinal resistances that are comparable to the resistance quantum h/e2 and independent of the channel length. Large nonlocal resistances (as large as 10^4 ohms) are observed in some but not all structures with separations between current and voltage that are large compared to the 2D mean-free path. The nonlocal transport is strongly suppressed by the onset of superconductivity below ~200 mK. The origin of these anomalous transport signatures is not understood, but may arise from coherent transport defined by strong spin-orbit coupling and/or magnetic interactions.