Scaling of 1/f noise in tunable break-junctions

TL;DR

This study investigates how 1/f voltage noise in gold nano-contacts varies with resistance, revealing a transition from diffusive to ballistic transport regimes through noise scaling behavior.

Contribution

It provides a detailed analysis of 1/f noise scaling in tunable break-junctions, connecting noise characteristics to transport regimes in nano-contacts.

Findings

Normalized noise scales as R^3 in low-resistance contacts

Normalized noise scales as R^1.5 in high-resistance contacts

Transition from diffusive to ballistic transport reflected in noise behavior

Abstract

We have studied the $1/f$ voltage noise of gold nano-contacts in electromigrated and mechanically controlled break-junctions having resistance values $R$ that can be tuned from 10 $\Omega$ (many channels) to 10 k$\Omega$ (single atom contact). The noise is caused by resistance fluctuations as evidenced by the $S_V\propto V^2$ dependence of the power spectral density $S_V$ on the applied DC voltage $V$. As a function of $R$ the normalized noise $S_V/V^2$ shows a pronounced cross-over from $\propto R^3$ for low-ohmic junctions to $\propto R^{1.5}$ for high-ohmic ones. The measured powers of 3 and 1.5 are in agreement with $1/f$-noise generated in the bulk and reflect the transition from diffusive to ballistic transport.