Electron-electron scatttering in Sn-doped indium oxide thick films

TL;DR

This study investigates electron-electron scattering in Sn-doped indium oxide thick films by measuring magnetoresistance at low temperatures, revealing a linear temperature dependence of dephasing rate consistent with 3D electron-electron interactions.

Contribution

It provides experimental evidence for the dominance of electron-electron scattering over electron-phonon interactions in low-carrier-density disordered conductors.

Findings

Dephasing rate varies linearly with T^{3/2}

Dephasing rate scales with k_F^{-5/2}l^{-3/2} at fixed T

Electron-electron scattering dominates dephasing in these films

Abstract

We have measured the low-field magnetoresistances (MRs) of a series of Sn-doped indium oxide thick films in the temperature $T$ range 4--35 K. The electron dephasing rate $1/\tau_{\varphi}$ as a function of $T$ for each film was extracted by comparing the MR data with the three-dimensional (3D) weak-localization theoretical predictions. We found that the extracted $1/\tau_{\varphi}$ varies linearly with $T^{3/2}$. Furthermore, at a given $T$, $1/\tau_{\varphi}$ varies linearly with $k_F^{-5/2}l^{-3/2}$, where $k_{F}$ is the Fermi wavenumber, and $l$ is the electron elastic mean free path. These features are well explained in terms of the small-energy-transfer electron-electron scattering time in 3D disordered conductors. This electron dephasing mechanism dominates over the electron-phonon ($e$-ph) scattering process because the carrier concentrations in our films are $\sim$ 3 orders of magnitude lower than those in typical metals, which resulted in a greatly suppressed $e$-ph relaxation rate.