In spite of Anderson's theorem, disorder is known to affect superconductivity in conventional s-wave superconductors. In most superconductors, the degree of disorder is fixed during sample preparation. Here we report measurements of the superconducting properties of the two-dimensional gas that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) in the (111) crystal orientation, a system that permits \emph{in situ} tuning of carrier density and disorder by means of a back gate voltage Vg. Like the (001) oriented LAO/STO interface, superconductivity at the (111) LAO/STO interface can be tuned by Vg. In contrast to the (001) interface, superconductivity in these (111) samples is anisotropic, being different along different interface crystal directions, consistent with the strong anisotropy already observed other transport properties at the (111) LAO/STO interface. In addition, we find that the (111) interface samples "remember" the backgate voltage VF at which they are cooled at temperatures near the superconducting transition temperature Tc, even if Vg is subsequently changed at lower temperatures. The low energy scale and other characteristics of this memory effect (<1 K) distinguish it from charge-trapping effects previously observed in (001) interface samples.
@article{arxiv.1704.01203,
title = {Superconductivity and Frozen Electronic States at the (111) LaAlO$_3$/SrTiO$_3$ Interface},
author = {S. Davis and Z. Huang and K. Han and Ariando and T. Venkatesan and V. Chandrasekhar},
journal= {arXiv preprint arXiv:1704.01203},
year = {2018}
}