Frictional drag between superconducting LaAlO$_3$/SrTiO$_3$ nanowires

TL;DR

This study investigates frictional drag effects between superconducting LaAlO₃/SrTiO₃ nanowires, revealing how quantum shot noise and thermal noise influence the drag signal, with implications for understanding electron-hole asymmetry in 1D superconductivity.

Contribution

It provides the first detailed measurement of frictional drag in superconducting LaAlO₃/SrTiO₃ nanowires, highlighting the roles of quantum and thermal noise and the impact of superconducting-normal transitions.

Findings

Antisymmetric drag component from quantum shot noise rectification.

Symmetric drag component from thermal noise during superconducting-normal transition.

Absence of symmetric drag in normal-superconducting nanowire pairs indicating electron-hole asymmetry.

Abstract

We report frictional drag measurements between two superconducting LaAlO$_3$/SrTiO$_3$ nanowires. In these experiments, current passing through one nanowire induces a voltage across a nearby electrically isolated nanowire. The frictional drag signal contains both symmetric and antisymmetric components. The antisymmetric component arises from the rectification of quantum shot noise in the drive nanowire by the broken symmetry in the drag nanowire. The symmetric component in the drag resistance is ascribed to rectification of thermal noise in the drive nanowire during superconducting-normal transition. The suppression of the symmetric component is observed when a normal nanowire is used as either a drag or drive nanowire with the other nanowire superconducting. The absence of symmetric drag resistance between a normal drag nanowire and a superconducting drive nanowire suggests a higher electron-hole asymmetry in the superconducting LaAlO$_3$/SrTiO$_3$ nanowire arising from the 1D nature of superconductivity at LaAlO$_3$/SrTiO$_3$ interface.