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Electron-hole liquid in a van der Waals heterostructure photocell at room temperature
November 8, 20194:00 pm – 5:00 pm (CDT)

Electron-hole liquid in a van der Waals heterostructure photocell at room temperature


Nathaniel Gabor (University of California, Riverside)


Ar. Abanov



Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

Condensation - the familiar process underlying the formation of clouds and the distillation of ethyl alcohol into whiskey - is the phase transition of gas into liquid droplets. In semiconductors, at sufficiently high electron-hole (e-h) densities or low temperatures, the gas of non-equilibrium electrons and holes may undergo condensation into one of several potential liquid-like phases. In this talk, I present recent results on the gas-to-liquid phase transition of electrons and holes in ultrathin van der Waals heterostructure photocells revealed through multi-parameter dynamic photoresponse microscopy (MPDPM). By combining rich visualization with comprehensive analysis of very large data sets acquired through MPDPM, we find that ultrafast laser excitation at a graphene-molybdenum ditelluride-graphene interface leads to the abrupt formation of ring-like spatial patterns in the photocurrent response as a function of increasing optical power. These patterns, together with extreme sublinear power dependence and picosecond-scale photocurrent dynamics, provide strong evidence for the formation of a two-dimensional e-h liquid. While our imaging experiments mark the first observation (in over 50 years of study) of an e-h liquid at room temperature, I will discuss our results within the greater context of strongly correlated electronic condensates.

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