Superconductivity in Bundles of Double-Wall Carbon Nanotubes

Abstract

We present electrical and thermal specific heat measurements that show superconductivity in double-wall carbon nanotube (DWCNT) bundles. Clear evidence, comprising a resistance drop as a function of temperature, magnetoresistance and differential resistance signature of the supercurrent, suggest an intrinsic superconducting transition below 6.8 K for one particular sample. Additional electrical data not only confirm the existence of superconductivity, but also indicate the Tc distribution that can arise from the diversity in the diameter and chirality of the DWCNTs. A broad superconducting anomaly is observed in the specific heat of a bulk DWCNT sample, which yields a Tc distribution that correlates well with the range of the distribution obtained from the electrical data. As quasi one dimensionality of the DWCNTs dictates the existence of electronic density of state peaks, confirmation of superconductivity in this material system opens the exciting possibility of tuning the Tc through the application of a gate voltage.Research Grants Council (Hong Kong, China) (HKUST9/CRF/08)Research Grants Council (Hong Kong, China) (SEG HKUST08)Research Grants Council (Hong Kong, China) (DSC104/05.SC01)Research Grants Council (Hong Kong, China) (VPAAO04/05.SC01)Research Grants Council (Hong Kong, China) (CA04/04.SC02)National Science Foundation (U.S.) (NSF/DMR 1004147)Brazil. National Council for Scientific and Technological DevelopmentShinshu University (Exotic NanoCarbon Project)Japan. Ministry of Education, Culture, Sports, Science and Technolog