Modification of a charged-Bose-gas model for observed room-temperature superconductivity in narrow channels through films of oxidised atactic polypropylene

TL;DR

This paper refines a model for room-temperature superconductivity in oxidised atactic polypropylene films by considering larger channel diameters and a different boson dispersion, supported by experimental and theoretical analysis.

Contribution

It introduces a modified Bose-gas model with a different dispersion relation and larger channel diameters to better explain observed room-temperature superconductivity in OAPP films.

Findings

Minimum filament number inferred from resistance data.

Modified dispersion relation affects superconductivity conditions.

Constraints on model parameters derived from combined theory and experiment.

Abstract

Reasons have been found for thinking that the minimum diameter of channels of a given length to support superconductivity at room temperature through films of oxidised atactic polypropylene (OAPP) is considerably larger than found in a model for Bose condensation in an array of nanofilaments [D.M. Eagles, Phil. Mag. 85, 1931 (2005)] used previously. This model was introduced to interpret experimental results dating from 1988 on OAPP. The channels are thought to be of larger diameter than believed before because, for an N-S-N system where the superconductor consists of an array of single-walled carbon nanotubes, the resistance, for good contacts, is R_Q/2N, where N is the number of nanotubes and R_Q=12.9 kOhm [See e.g. M. Ferrier et al., Solid State Commun. 131, 615 (2004)]. We assume this would be 2R_Q/N for a triplet superconductor with all spins in the same direction and no orbital degeneracy, which may be the case for nanofilaments in OAPP. Hence one may infer a minimum number of filaments for a given resistance. In the present model, the E(K) curve for the bosons is taken to be of a Bogoliubov form, but with a less steep initial linear term in the dispersion at T_c than occurs at low T. This form is different from the simple linear plus quadratic dispersion, with a steeper initial slope, used in my 2005 paper. A combination of theory and experimental data has been used to find approximate constraints on parameters appearing in the theory.