Lu Chen: Ultrafast Optical Response of Graphene/LaAlO3/SrTiO3 Heterostructure

Graphene is a promising tunable plasmonic material in the terahertz regime. Plasmons can be induced in graphene by femtosecond laser excitation, and their resonance frequency can be gate-tuned over a broad terahertz range. Another 2D electron system, the complex-oxide heterostructure LaAlO3/SrTiO3, has been shown to exhibit great promise for control and detection of broadband THz emission at extreme nanoscale dimensions. Recently, we have successfully integrated these two platforms: we have created graphene/LaAlO3/SrTiO3 structures with high mobility in the graphene channel and oxide nanostructures directly underneath the graphene layer. Here we describe new experiments that probe graphene plasmonic behavior using this nanoscale THz spectrometer using ultrafast optical techniques. This unprecedented control of THz radiation at 10 nm length scales creates a pathway toward hybrid THz functionality in graphene/LaAlO3/SrTiO3 heterostructures.