Photocurrents in Plasmonic Metals. Spectral and material dependence.*

Significant electrical effects associated with plasmonic excitations present interest for various applications including plasmonic biosensors with compact electric detection. The origin of these effects is not fully clear as the magnitude of the photocurrents significantly exceeds the predictions of the theoretical momentum loss approach.  In the experiment, we study photoinduced voltages at plasmon resonance conditions as a function of the wavelength in various metals, including silver, gold, aluminum, copper, platinum, and permalloy.  The effects are found to be strongly different in different materials; they increase in relative magnitude upon decreasing wavelength toward the localized plasmon resonance.  Experimental data is used to develop a better understanding the nature of plasmon-induced electrical effects and to characterize them for possible applications.