Long-range non-Coulombic electron-electron interactions between coupled LaAlO$_3$/SrTiO$_3$ nanowires

TL;DR

This study demonstrates long-range, non-Coulombic electron-electron interactions in LaAlO$_3$/SrTiO$_3$ nanowires, revealed through frictional drag measurements that challenge traditional Coulomb interaction decay expectations.

Contribution

It provides experimental evidence for a novel long-range non-Coulombic interaction in oxide nanowires, expanding understanding of electron interactions in complex materials.

Findings

Frictional drag persists over large distances, nearly independent of separation.

Long-range interactions are observed even with an electrically grounded wire.

Results suggest a new type of electron-electron interaction beyond Coulomb forces.

Abstract

The LaAlO$_3$/SrTiO$_3$ system exhibits unusual magnetic and superconducting behavior arising from electron-electron interactions whose physical origin is not well understood. Quantum transport techniques, especially those involving mesoscopic geometries, can offer insight into these interactions. Here we report evidence for long-range electron-electron interactions in LaAlO$_3$/SrTiO$_3$ nanowires, measured through the phenomenon of frictional drag, in which current passing through one nanowire induces a voltage across a nearby electrically isolated nanowire. Frictional drag mediated by the Coulomb interaction is predicted to decay exponentially with interwire separation, but with the LaAlO$_3$/SrTiO$_3$ nanowire system it is found to be nearly independent of separation. Frictional drag experiments performed with three parallel wires demonstrates long-range frictional coupling even in the presence of an electrically grounded central wire. Collectively, these results provides evidence for a new long-range non-Coulombic electron-electron interaction unlike anything previously reported for semiconducting systems.