Nanoscale control of oxide interface conduction in graphene-complex-oxide heterostructures*

Graphene is a promising material for high-speed optoelectronic devices such as THz modulators and detectors. Recently, broadband THz emission and detection can be achieved with nanostructures at the LaAlO$_3$/SrTiO$_3$ interface \footnote{Y. Ma, \textit{et al.}, \textit{Nano Lett.} \textbf{13}, 2284 (2013)}. We have mechanically exfoliated single layer and multilayer graphene on top of 3.4 unit cell LaAlO$_3$/SrTiO$_3$ and successfully sketched nanowires in the 2DEG underneath graphene using conductive AFM lithgraphy \footnote{C. Cen, \textit{et al.}, \textit{Nat. Mater.} \textbf{7}, 298 (2008)}. Raman and AFM investigations confirm that the graphene quality and surface morphology remain unaltered by the writing process. These first experimental demonstrations of integrating graphene and LaAlO$_3$/SrTiO$_3$ are promising for future DC-THz photonic applications.