Electron mobility of a two-dimensional electron gas at the interface of SrTiO$_3$ and LaAlO$_3$

TL;DR

This paper models the electron mobility at the LaAlO₃/SrTiO₃ interface using a three-band Boltzmann approach, accounting for anisotropic dielectric properties and impurity scattering, and finds a mobility inversely proportional to the cube of carrier density.

Contribution

It introduces a detailed three-band Boltzmann model that incorporates anisotropic dielectric screening and multiband effects to explain electron mobility behavior at the interface.

Findings

Mobility varies as n_{2D}^{-3}, matching experiments.

Dielectric anisotropy influences screening and mobility.

Multiband interactions are significant in mobility calculations.

Abstract

We calculate the mobility of a two-dimensional electron gas residing at the interface of LaAlO$_{3}$/SrTiO$_{3}$ following a three band Boltzmann approach at low temperature, where carrier-charged impurity scattering process is assumed to be dominant. We explain the anisotropic characteristic of the dielectric function, which is a consequence of elliptical bands close to Fermi surface. The screening effect, which weakens the long-range Coulomb interaction of the electron-impurity is considered within the random phase approximation. Working at carrier densities high enough to neglect the spin-orbit induced splitting of the bands, we find that the mobility varies inversely with the cubic power of the carrier density ($n_{2D}^{-3}$) in good agreement with the experimental results. We also investigate the role of variable dielectric constant of SrTiO$_{3}$, the multiband nature of the system and interband interactions in exploring this result.