Journal of Nanomedicine & Nanotechnology

Superconductivity and unusual magnetic behavior in amorphous carbon

4^th International Conference on Nanotek & Expo

December 01-03, 2014 DoubleTree by Hilton Hotel San Francisco Airport, USA

Israel Felner

Keynote: J Nanomed Nanotechnol

Abstract:

Traces of superconductivity (SC) at elevated temperatures (up to 65 K) were observed by magnetic measurements in three different in homogeneous sulfur doped amorphous carbon (a-C) systems: (a) in commercial and (b) synthesized powders and (c) in a-C thin films. (a) Studies performed on commercial (a-C) powder which contains 0.21% of sulfur, revealed traces of non-percolated superconducting phases below Tc=65 K. The SC volume fraction is enhanced by the sulfur doping. (b) a-C powder obtained by pyrolytic decomposition of sucrose did not show any sign for SC above 5 K. This powder was mixed with sulfur and synthesized at 400?C (a-CS). The inhomogeneous products obtained, show traces of SC phases at TC=17 and 42 K. (c) Non-superconducting composite a-C-W thin films were grown by electron-beam induced deposition. SC emerged at Tc=34.4 K only after heat treatment with sulfur. Other parts of the pyrolytic a-CS powder, show unusual magnetic features. (i) Pronounced irreversible peaks around 55-75 K appear in the first zero-field-cooled (ZFC) sweep only. Their origin is not known. (ii) Unexpectedly these peaks are totally suppressed in the second ZFC runs measured a few minutes later. (iii) Around the peak position the field-cooled (FC) curves cross the ZFC plots (ZFC>FC). These peculiar magnetic observations also ascribed to a-CS powder prepared from the commercial a-C powder and are connected to each other. All SC and magnetic phenomena observed are intrinsic properties of the sulfur doped a-C materials. It is proposed that the a-CS systems behave similarly to well-known high TC curates and/or pnictides in which SC emerges from magnetic states.

Biography :

Israel Felner has completed his PhD at the age of 32 years from the Hebrew University (HU) Jerusalem and postdoctoral studies from University of California San-Diego. He was the director of Physics studies in HU. He has published more than 470 papers in reputed journals and serves as an editorial board member of three journals.