Relaxation and a non-local, resistivity boundary layer in superconductors

Abstract

Superconductors like other solids cannot relax instantaneously from thermally excited (disturbed) states to thermodynamic equilibrium. In this paper, relaxation of a multi-filamentary and of a thin film superconductor from thermal excitations is simulated. Absorption of radiation or, under conductor movement, release and transformation of mechanical tension to thermal energy are examples. The paper applies numerical simulations of superconductor energy states, as many-particle systems, under basic thermodynamic and standard, multi-component heat transfer principles (solid conduction plus radiation in thin films). A recently described microscopic stability model and application of a traditional, continuum cell model allows to explain curvature of the resistance vs. temperature excursion below critical temperature, TCrit, and suggests an alternative to standard explanation of increased electrical conductivity at temperature exceeding TCrit. A non-local, resistivity boundary layer (a temperature uncertainty) is observed near critical temperature within which the resistivity curve smoothly approaches, from the superconducting state, the normal conduction resistivity. Keywords Superconductor; phase transition; relaxation; critical current density; critical temperature; thermal fluctuations; boundary layers