Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 61: TR: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3
TT 61.7: Vortrag
Freitag, 18. März 2011, 12:15–12:30, HSZ 304
Transport measurements on single Bi nanowires at temperatures below 1 K — •C. Reiche1, T. Peichl1,2, S. Mueller3, M.E. Toimil-Molares3, R. Neumann3, and G. Weiss1,2 — 1Physikalisches Institut, KIT Karlsruhe — 2Centrum für funktionelle Nanostrukturen, KIT Karlsruhe — 3GSI Darmstadt
With its large Fermi wavelength and long mean free paths, Bi is a fascinating metal for studies of transport phenomena in samples of reduced dimensions. Previous transport measurements on bundles of crystalline Bi wires with diameters around 100 nm found a remarkable decrease of sample resistance below 300 mK. Localization effects were ruled out as a cause of this decrease, so one might speculate that surface states are able to change the electronic structure of Bi in a way that it may exhibit superconductive properties. Very recently other groups have conducted measurements on single Bi nanowires and found that their data also fit superconductivity, probably induced by a surface layer of Bi oxide or other contaminants on the surface of the wires. Our samples are produced by a template method, using an ion track etched polycarbonate membrane. It has been shown that using these membranes it is possible to extract single wires without oxidation of the surface. From these samples we are preparing single Bi wires and contact them in 2- or 4-point contact geometry. We are conducting transport measurements to study the influence of different surface layers on the transport properties of the Bi wires at temperatures below 1 K. Furthermore we are gathering additional data to decide if the observed behavior may be attributed to superconductivity.