Growth-induced electron mobility enhancement at the LaAlO${}_3$/SrTiO${}_3$ interface

We have studied the electronic properties of the 2D electron liquid present at the LaAlO${}_3$/SrTiO${}_3$ interface in series of samples prepared at different growth temperatures. We observe that interfaces fabricated at 650{\deg}C exhibit the highest low temperature mobility ($\approx 10000 \textrm{ cm}^2/$\text{Vs}$$)andthelowestsheetcarrierdensity($\approx 5\times 10^{12} $\text{ cm}$^{-2}$). These samples show metallic behavior and Shubnikov-de Haas oscillations in their magnetoresistance. Samples grown at higher temperatures (800-900{\deg}C) display carrier densities in the range of $\approx 2-5\times {10}^{13}{\text{ cm}}^{-2}$ and mobilities of $\approx 1000 $\text{ cm}$^2/$\text{Vs}$$ at 4K. Reducing their carrier density by field effect to $8\times {10}^{12}{\text{ cm}}^{-2}$ lowers their mobilites to $\approx 50{\text{ cm}}^2\mathrm{/}\text{Vs}$ bringing the conductance to the weak-localization regime.