Determination of the phase coherence length of PdCoO$_2$ nanostructures

TL;DR

This study measures the phase coherence length in PdCoO$_2$ nanostructures, revealing defect scattering at twin boundaries as a key factor, and suggests pathways for creating phase coherent quantum devices using this material.

Contribution

It provides the first determination of the phase coherence length in PdCoO$_2$ thin films through conductance fluctuation analysis, highlighting defect scattering effects.

Findings

Phase coherence length is approximately 100 nm.

Weak temperature dependence indicates defect scattering dominates.

Potential for phase coherent devices by controlling twin boundaries.

Abstract

The two-dimensional layered compound PdCoO$_2$ is one of the best oxide conductors, providing an intriguing research arena opened by the long mean free path and the very high mobility of ~51000 cm2/Vs. These properties turn PdCoO$_2$ into a candidate material for nanoscale quantum devices. By exploring universal conductance fluctuations originating at nanoscale PdCoO$_2$ Hall-bar devices, we determined the phase coherence length of electron transport in c-axis oriented PdCoO$_2$ thin films to equal ~100 nm. The weak temperature dependence of the measured phase coherence length suggests that defect scattering at twin boundaries in the PdCoO$_2$ thin film governs phase breaking. These results suggest that phase coherent devices can be achieved by realizing the devices smaller than the size of twin domains, via refined microfabrication and suppression of twin boundaries.