THz investigations of graphene-complex-oxide heterostructures

The unique and multifaceted properties of graphene have fascinated scientists and engineers for a decade now. A new frontier in research concerns properties of graphene in the THz-IR region, where the collective excitation of graphene 2D electron gas (2DEG) into plasmonic waves has proven the salient feature.\footnote{L. Ju, \textit{et al.}, Nat. Nanotechnol. \textbf{6}, 630 (2011)} Complex oxide heterostructures (e.g., LaAlO$_{3}$/SrTiO$_{3}$, LAO/STO) also support a 2DEG with high carrier densities and expected plasmonic behavior. A unique feature of the LAO/STO system is the ability to control the electron density with nanoscale precision.\footnote{C. Cen, \textit{et al.}, Nat. Mater. \textbf{7}, 298 (2008)} In addition, a method for sourcing and detecting broadband THz emission from LAO/STO nanojunctions has been recently demonstrated.\footnote{Y. Ma, \textit{et al.}, Nano Lett. \textbf{13}, 2284 (2013)} Here we describe initial efforts to investigate the THz properties of graphene-complex oxide (GCO) heterostructures. We envision that the proposed graphene plasmonic devices in the GCO will help to lay the foundation for a host of powerful THz-IR technologies for signal processing, imaging, spectroscopy and chemical sensing.