MAT Seminar

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ABSTRACT: Miniaturization technology has become an emerging field due to the astonishing trend of the electronic and devices' diminishing down to the nano scale since the beginning of the last decade. The obstacle of today's information technology is the diffraction limit of light, which prevents information transfer at the nano scale. Plasmons which are coherent collective oscillations of quasi-free electrons in a metal volume or on a surface offer numerous application possibilities to transfer information beyond the diffraction limit. However, there are many questions to be answered in the young field of plasmonics in terms of characteristics and applications.

This research concentrates on different plasmonic phenomena which are observed with a transmission electron microscope (TEM) in combination with electron energy loss spectroscopy (EELS) and energy-filtering transmission electron microscopy (EFTEM) techniques offering high energy and spatial resolution. Plasmonic coupling behaviour of nanoholes having rectangular and circular shapes were investigated using these techniques. The electromagnetic nature of the observed plasmonic eigenmodes was unveiled with different simulation techniques based on  finite element method (FEM) and three-dimensional finite-difference time-domain methods (3D-FDTD).

First, hybridization of closely spaced rectangular nanoslits was analyzed in the framework of Babinet's principle. (1) The research proceeds with the first demonstration of toroidal modes in a metal ring formed by an oligomer of holes at optical wavelengths. (2) It is expected that the findings in this research bear great potential for novel applications such as information technology, magnetic data storage, medical science and solar cell engineering.

References:
1.      B. Ögüt, R. Vogelgesang, W. Sigle, N. Talebi, C. T. Koch, P. A. van Aken, ACS Nano 5 (8) 2011, 6701-6706.
2.      B. Ögüt, N. Talebi, R. Vogelgesang, W. Sigle, P. A. van Aken, Nano Letters 12 (10) 2012, 5239-5244.