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

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.

7 pages, 5 figures