Electron-electron scattering and nonequilibrium noise in Sharvin contacts

TL;DR

This paper analyzes how electron-electron interactions in ballistic microcontacts influence electrical noise and conductance, revealing temperature and voltage-dependent behaviors and shot noise contributions.

Contribution

It provides a theoretical calculation of noise and conductance considering electron-electron scattering in wide ballistic contacts, highlighting the impact of geometry and inelastic effects.

Findings

Inelastic correction to conductance is proportional to T at low voltages.

At high voltages, the correction scales with |V|.

Shot noise persists due to electron collisions despite momentum conservation.

Abstract

We consider wide ballistic microcontacts with electron-electron scattering in the leads and calculate electric noise and nonlinear conductance in them. Due to a restricted geometry the collisions of electrons result in a shot noise even though they conserve the total momentum of electrons. We obtain the noise and the conductivity for arbitrary relations between voltage V and temperature T. The positive inelastic correction to the Sharvin conductance is proportional to T at low voltages eV << T, and to |V| at high voltages. At low voltages the noise is defined by the Nyquist relation and at high voltages the noise is related with the inelastic correction to the current by the Shottky formula S_{in} = 2eI_{in}.