Abstract: Electrical or electro-mechanical apparatuses are disclosed that include a plurality of superconducting nanotubes or a plurality of superconducting nanotube bundles, especially superconducting carbon nanotubes and a stabilizing means or structure, where the nanotubes are maximally proximate and where the means stabilizes the nanotubes to increase mechanical durability. Methods of sorting nanotubes based on their conductive properties are also disclosed.

Abstract: Disclosed are high temperature and/or room temperature superconducting carbon nanotube compositions having either a critical doping range, a critical chirality or a mixture thereof, high temperature superconducting graphite compositions having a critical doping range, methods of achieving a phase-coherent, near zero resistivity superconducting state in multiwalled carbon nanotubes and bundles of superconducting carbon nanotubes, methods of achieving a large positive magnetoresistance in bundles of superconducting carbon nanotubes, and methods for making and using such nanotubes or bundles. Disclosed also are devices and apparatuses (e.g., magnetic reading heads, magnetic switch devices, magnetic imaging devices, and superconducting quantum interference devices) comprising superconducting carbon nanotubes and/or bundles of superconducting carbon nanotubes.