Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 33: Postersession Correlated Electrons: Metal Insulator Transition, Spin Systems and Itinerant Magnets

TT 33.3: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Co-tunneling in two-dimensional lattices of EBID-nanoparticles — •Roland Sachser, Fabrizio Porrati, and Michael Huth — Physikalisches Institut, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany

W-based granular metals have been prepared by electron beam induced deposition (EBID) from the tungsten-hexacarbonyl-precursor W(CO)₆. In EBID the electron beam raster process is reflected in the deposit in the limit of large dwell times. This results in a two-dimensional lattice of mesoscopic granular metal islands, in which metallic nanocrystals are separated by an insulating matrix. The islands have a high tungsten-content and therefore a high intrinsic conductivity. To investigate the transport mechanism we performed transport measurements over a temperature range from 2K to 260K. For low temperatures we observe a σ∼ exp(−(T₀/ T)^1/2) dependence of the conductivity. The current-voltage-characteristics do not show a Coulombblockade. We interpret our measurements for low temperatures as a fingerprint of co-tunneling. By changing the electron beam parameters the size of the islands and the lattice constant can be varied. In this way it is possible to adjust the coupling between the islands and influence the transport mechanism.