Superfluid density of a pseudogapped superconductor near the superconductor-insulator transition.

We analyze the critical behavior of the superfluid density ps in strongly disordered superconductors near the superconductor-insulator transition and compare it with the behavior of the spectral gap Δ for collective excitations. We show that, in contrast to conventional superconductors, the superconductors with preformed pairs display an unusual scaling relation ps ∞ Δ2 close to the superconductor-insulator transition. This relation has been reported in very recent experiments. [ABSTRACT FROM AUTHOR]