### Session T41: Focus Session: Search for New Superconductors - Nanotubes and Fullerides

2:30 PM–5:18 PM, Wednesday, March 17, 2010
Room: F152

Chair: Anvar Zakhidov, University of Texas at Dallas

Abstract ID: BAPS.2010.MAR.T41.1

### Abstract: T41.00001 : Search for Superconductivity in Charge Doped Composites of Carbon Nanotubes and Fullerides

2:30 PM–2:42 PM

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#### Authors:

Austin Howard
(The University of Texas at Dallas)

Javier Carretero-Gonzalez
(The University of Texas at Dallas)

Elizabeth Castillo-Martinez
(The University of Texas at Dallas)

Ray Baughman
(The University of Texas at Dallas)

Anvar Zakhidov
(The University of Texas at Dallas)

The motivation of this study is to develop a highly sensitive method of microwave absorption in low magnetic fields (LFMA), combined with SQUID magnetometry, for searching for superconducting phases in nanocomposites in which carrier concentration is changed by in-situ doping. The unzipped ribbons of multiwalled carbon nanotubes (MWCNTs) (which are stacks of graphene ribbons) are infiltrated by $\mbox{C}_{60}$ fullerenes and doped chemically (by alkali metals) and electrochemically to modulate the carrier concentration. It is demonstrated that hysteretic LFMA appearing below $T_c$ is indeed a highly sensitive test for negligibly small superconducting (SC) phases (\mbox{$\sim10^{-11}\ \mbox{g}$}), and multi-phase SC composites with several $T_c$ can be detected and separated. At the same time, non-SC signals (which are quite similar to SC LFMA) have been found from samples containing magnetic nanoclusters (Fe, Ni/Co, etc.) which are catalyst residuals in CNT synthesis. The strategies of differentiating SC LFMA from magnetic LFMA by complementary SQUID/transport studies are suggested.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.T41.1