Abstract Submitted to the    NANOTUBE'06 Conference:

High-Tc Superconductivity in Entirely End-bonded Multi-walled nanotubes

Junji Haruyama ¹, Izumi Takesue ², Naoyoshi Murata ¹, Shohei Chiashi ³, Shigeo Maruyama ³, Toshiki Sugai ⁴, Hisanori Shinohara ⁴

¹ Aoyama Gakuin University
² Waseda University
³ Tokyo University
⁴ Nagoya University

J-haru@ee.aoyama.ac.jp

XIV. Transport in Nanotubes

One-dimensional (1D) systems face some obstructions that prevent the emergence of superconductivity, such as Tomonaga-Luttinger liquid states and Peierls transition. Carbon nanotubes (CNs) are one of the best candidates for investigating the possibility of 1D superconductivity and its interplay with such obstructions. Only two groups to our knowledge, however, have experimentally reported superconductivity in CNs [1],[2]. In contrast, interestingly B-doped diamond and CaC₆ could exhibit superconductivity with T_c of about 11K [3].
Here, we report that entirely end-bonded multi-walled CNs (MWNTs) can exhibit superconductivity with a T_c as high as 12 K [4], which is approximately 30 times greater than T_c reported in [1]. We also find that the emergence of this superconductivity is very sensitive to the junction structures of the Au electrode/MWNTs. This reveals that only MWNTs with optimal numbers of electrically activated shells can allow superconductivity due to intershell effects. Recent measurement results in magnetization will be also shown.

[1] M. Kociak, et al., Phys. Rev. Lett. 86, 2416 (2001)
[2] Z. K. Tang, et al., Science 292, 2462 (2001)
[3] E.A.Ekimov et al., Nature (London) 428, 542 (2004); T.E.Weller et al., Nature Physics 1, 39 (2005)
[4] J.Haruyama et al., Phys. Rev. Lett. 96, 057001 (2006)

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