Regularization of the density-of-states fluctuation contribution in a magnetic field

The fit of the experimental data on c-axis magnetoresistance of high-temperature superconductors above the transition temperature with the theory based on, the fluctuation renormalization of the one-electron density of states (DOS) is excellent in weak magnetic fields but meets the noticeable difficulties in the region of strong fields. This is due to the formal divergence of the DOS contribution to conductivity and the dependence of the cutoff parameter on the magnetic field itself. We propose the scheme of the regularization of the problem. This permits us to obtain the expression for the magnetic-field-dependent part of the DOS conductivity as a convergent series independent of cutoff. We also calculate analytically the asymptotic for all regions of magnetic fields. The results demonstrate the robustness of the DOS contribution with respect to the magnetic-field effect: in strong field's [H>H-c2(T- T-c)] it decreases logarithmically, only while Aslamazov-Larkin and anomalous Maki-Thompson contributions diminish as powers of H-c2/H. [S0163-1829(98)03546-2].