Growth-induced electron mobility enhancement at the LaAlO₃/SrTiO₃ interface

We have studied the electronic properties of the 2D electron liquid present at the LaAlO₃/SrTiO₃ interface in series of samples prepared at different growth temperatures. We observe that interfaces fabricated at 650 °C exhibit the highest low temperature mobility (≈ 10 000 cm² V^-1s-¹) and the lowest sheet carrier density (≈ 5 × 10¹² cm^-2). These samples show metallic behavior and Shubnikov-de Haas oscillations in their magnetoresistance. Samples grown at higher temperatures (800-900 °C) display carrier densities in the range of ≈ 2-5 × 10¹³ cm^-2 and mobilities of ≈ 1000 cm 2 V^-1s^-1 at 4 K. Reducing their carrier density by field effect to 8 × 10¹² cm^-2 lowers their mobilities to ≈ 50 cm 2 V^-1s^-1 bringing the conductance to the weak-localization regime.