Resistivity Anomaly Observed in Nano-Structured C60-SAM on Ultrathin Au Films

Nobuyuki Iwata ,  Takuto Sakuma ,  Tuo Fanj ,  Hiroshi Yamamoto 

Nihon University, College of Science and Technology, Department of Electronics and Computer Science, 7-24-1, Narashinodai, Funabashi-shi 274-8501, Japan


Little or Ginzburg have discussed a possibility of room temperature superconductivity (RTS) by an excitonic mechanism in low dimensional system[1-2]. In order to realize the RTS we prepared nano-structured C60 derivatives self-assembly monolayer (C60-SAM) on a ultrathin Au film.
Thickness of the Au films must be in the order of nm for the enhancement of interactions between excitons in the C60 derivatives and conducting electrons in the Au. Such the Au films are prepared on annealed MgO single crystals, of which surfaces showed flatness in atomic level with a step-terrace structure. The Au films grew along the steps of the MgO. The Au/MgO substrates are soaked in benzene solution of 0.01 mM C60 derivatives to obtain C60-SAM. Surface morphology is observed by AFM.
The Au/Mo electrodes and ultrathin Au area are simultaneously obtained on the substrates by RF magnetron sputtering through a metal mask. Behind the mask random kinetic motions of sputtered Au particles resulted in the deposition of ultrathin Au films. The thickness of the ultrathin Au was very sensitive to the gap distance between the mask and the substrate.
When resistivity of the prepared sample is measured, an appearance of the superconductivity will be characterized as an anomalous decrease in the resistivity because of inhomogeneous thickness of the Au films. Several samples revealed such the resistivity anomaly in the high temperature range above 100 K to 200 K. The appearance of the anomaly strongly depended on the Au thickness of the samples. Furthermore such the anomaly vanished as increasing measurement current, which may indicate the break of superconductivity by exceeding Ic. We intend to attempt increase of the anomaly temperature up to room temperature by optimizing the Au film thickness and also to measure magnetic properties to define the superconductivity.
[2]V.L.Ginzburg et al.:Contemp.Phys.9(1968)355


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Presentation: oral at E-MRS Fall Meeting 2004, Symposium E, by Nobuyuki Iwata
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-28 09:37
Revised:   2009-06-08 12:55