Massless Mode of Abrikosov Flux Lattice

Abstract
The massless mode of harmonic fluctuations of the Abrikosov flux lattice is studied in detail within the GL theory. Without relying on the usual approximation to neglect all but the lowest Landau level we prove exactly that no terms quadratic in k 0 appear in the spectrum of this mode where k 0 is the wave vector of fluctuations perpendicular to the flux lines. This mode is identified as the incompressible shear lattice mode even if the GL parameter is finite and all fluctuations of the gauge field are taken into account. Some problems concerning this mode are also discussed.