Room-temperature superconductivity in ultra-thin carbon nanotube zeolite composites: a conventional or unconventional superconductor?

Abstract

The recent report of signs of room-temperature superconductivity in ultrathin single-walled carbon nanotubes (CNT) of types (2,1) and (3,0) holds significant promise for energy applications due to their ability to conduct current without dissipation. However, the McMillan Tc formula fails to calculate their superconducting transition temperatures (Tc) accurately, which raises an important question: what is the pairing mechanism driving their room-temperature superconductivity? To explore this further, we first investigate whether the strong curvature of ultrathin CNT leads to exotic phenomena in unconventional superconductors. If no evidence of these exotic characteristics is found and the McMillan formalism indicates that it is not a BCS-type superconductor, could we be observing a new class of unconventional superconductivity that functions independently of phonons and typical exotic features? In this paper, we demonstrate that factors such as the chiral angle of CNT, boron dopants and lattice regularity can be used to tune the theoretical Tc to experimental values. Our finding suggests that combining CNT with a harder substrate could be vital for further enhancing Tc while minimizing lattice distortion under doping. We propose a reconsideration of the common belief regarding whether the McMillan and BCS Tc formulas are adequate for classifying materials as BCS or non-BCS superconductors.