Gravitomagnetism and magnetic permeability in superconductors

Abstract

Li and Torr [Phys. Rev. B 46, 5489 (1992)] have developed theoretical models to estimate the magnitude of gravitomagnetic effects in superconductors. The magnitude deduced, however, is grossly overestimated, because the authors have misinterpreted the meaning of the magnetic permeability, \ensuremath{\mu}, as it is commonly used by experimentalists describing the Meissner effect in bulk superconducting samples. The authors have also proposed flawed models of the microscopic dynamics of superconductors to support their error. Ambiguity in the common usage of the magnetization field (M), magnetic susceptibility (\ensuremath{\chi}), and permeability (\ensuremath{\mu}), to describe the macroscopic and microscopic behavior of superconductors is partly to blame; a simple heuristic model is presented here to clarify the meaning of these terms.