Quantum Conductance Effects in Charge Transfer Plasmons

Alejandro Manjavacas Department of Physics and Astronomy, Rice University, Houston, Texas, USA Vikram Kulkarni Department of Physics and Astronomy, Rice University, Houston, Texas, USA Peter Nordlander Department of Physics and Astronomy, Rice University, Houston, Texas, USA

Localized surface plasmon resonances (LSPR) are a subject of intense experimental and theoretical research interest. Thanks to their exceptional light capturing and focusing capabilities, LSPR have found applications in catalysis, solar energy, cancer therapy, or surface enhanced Raman spectroscopy (SERS). An LSPR of particular interest is the charge transfer plasmon (CTP). This mode appears when two plasmonic nanoparticles are bridged by a conductive junction. Due its origin, the CTP is extraordinarily sensitive to the conductive properties of the junction. Here [1] we perform a first-principles investigation of the properties of the CTP of a system composed of two gold nanospheres bridged by a quantum dot, using the time dependent density functional theory (TDDFT). By modulating the electronic structure of the quantum dot we are able to effectively turn the CTP on and off. Specifically, the CTP emerges only when a quantum dot energy level is resonant with the Fermi energy of the plasmonic nanoparticles. This behavior is analogous to DC transport theory, where the conductance through the junction is given by the number of conducting channels multiplied by the quantum unit of conductance. Interestingly, we find that the conductance through the junction is on the order of the quantum unit of conductance. This work is of great interest to the future design of plasmonic and molecular electronic systems.

[1] V. Kulkarni, A. Manjavacas, and P. Nordlander, in preparation (2015).

alejandro.manjavacas@rice.edu









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