Fluctuation of the Order Parameter and Hall Effect

Abstract

Hall conductivity σxy in the fluctuating dirty superconductors is examined microscopically above the critical temperature Tc where fluctuation effects are important.In weak field limit, i.e., DeH/T ≪≪ η (D: diffusion constant, η= (T-Tc)/Tc), the Hall angle in thin films with thickness d is given by where ωc = eH/mc, η0 = e2/16dσ0, σ0 = (ne2/m)τ (τ: relaxation time) and α= (2/πgN) (g: BCS coupling constant, N: state density at the Fermi energy) and δ is a pair-breaking parameter. The second term in the numerator comes from the Maki process, whereas the last is due to the AL process, which shows that the gigantic Meissner currents contribute to Hall effect in the fluctuating region. The sign of the contributions from such diamagnetic currents depends on the sign of energy derivative of the density of state function at the Fermi energy.