Short-wavelength cutoff effects in the ac fluctuation conductivity of superconductors

The short-wavelength cutoff has been introduced in the calculation of the ac fluctuation conductivity of superconductors. It is shown that a finite cutoff leads to a breakdown of the scaling property in frequency and temperature. Also, it increases the phase $\phi$ of the complex conductivity $(\tan \phi ={\sigma }_2/{\sigma }_1)$ beyond $\pi /4\mathrm{}$ at $T_c.$ Detailed expressions containing all essential parameters are derived for three-dimensional isotropic and anisotropic fluctuation conductivity. In the two-dimensional case we obtain individual expressions for the fluctuation conductivity for each term in the sum over discrete wave vectors perpendicular to the film plane. A comparison of the theory to the experimental microwave fluctuation conductivity is provided.