Effect of screening on shot noise in diffusive mesoscopic conductors

TL;DR

This paper investigates how screening affects shot noise in diffusive mesoscopic conductors at finite frequencies, revealing a transition from the known 2eI/3 level to a new fundamental level eI at high frequencies.

Contribution

It provides a detailed analysis of shot noise behavior considering screening effects at finite frequencies in different conductor geometries.

Findings

At low frequencies, shot noise is 2eI/3, regardless of screening.

At high frequencies, shot noise approaches eI in certain conductor geometries.

Screening significantly alters shot noise behavior at frequencies comparable to the inverse Thouless time.

Abstract

Shot noise in diffusive mesoscopic conductors, at finite observation frequencies $\omega $ (comparable to the reciprocal Thouless time $\tau_T^{-1}$), is analyzed with an account of screening. At low frequencies, the well-known result $S_I(\omega)=2eI/3$ is recovered. This result is valid at arbitrary $\omega \tau_T$ for wide conductors longer than the screening length. However, at least for two very different systems, namely, wide and short conductors, and thin conductors over a close ground plane, noise approaches a different fundamental level, $S_I(\omega) = eI$, at $\omega \tau _T\gg 1$.