Anisotropic superconductivity of nanowires at LaAlO$_3$/SrTiO$_3$(110) heterointerface

A two-dimensional electron gas has recently been discovered at the interface of LaAlO$_3$ grown on the (110) surface of SrTiO$_3$.\footnote{A. Annadi, \textit{et al.}.\textit{Nature Commun.} \textbf{4}, 1838 (2013)} The conductivty of the 2DEG at this interface is anisotropic along different crystallographic directions. Using conducting AFM lithography we write interfacial nanowires along the (001) and (1-10) directions on 3-unit cell LaAlO$_3$/SrTiO$_3$(110). Similar to the anisotropic conductivity found in the normal state, we observe anisotropy of the superconducting properties of the two types of wire: the upper critical magnetic field of nanowires along the (001) direction is higher than those along (1-10) direction. This observation can be related to the anisotropic orbital binding of Ti and O atoms and the differences in the spin-orbit coupling along the two different directions.