Anisotropic superconductivity and frozen electronic states at the (111) LaAlO3/SrTiO3 interface

We report measurements of the superconducting properties of the two-dimensional (2D) gas that forms at the interface between ${\mathrm{LaAlO}}₃$ (LAO) and ${\mathrm{SrTiO}}₃$ (STO) in the (111) crystal orientation, a system that permits in situ tuning of carrier density and disorder by means of a back-gate voltage ${V}_g$. Like the (001) oriented LAO/STO interface, superconductivity at the (111) LAO/STO interface can be tuned by ${V}_g$. The 2D superconductivity in these (111) LAO/STO samples shows an in-plane anisotropy, being different along different interface crystal directions, and ``remembers'' the disorder landscape at which they are cooled through the superconducting transition. The low energy scale and other characteristics of this memory effect distinguish it from charge-trapping effects previously observed in (001) interface samples.