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

The fit of the experimental data on c-axis magnetoresistance of high-temper ature superconductors above the transition temperature with the theory base d on, the fluctuation renormalization of the one-electron density of states (DOS) is excellent in weak magnetic fields but meets the noticeable diffic ulties 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 p arameter on the magnetic field itself. We propose the scheme of the regular ization of the problem. This permits us to obtain the expression for the ma gnetic-field-dependent part of the DOS conductivity as a convergent series independent of cutoff. We also calculate analytically the asymptotic for al l regions of magnetic fields. The results demonstrate the robustness of the DOS contribution with respect to the magnetic-field effect: in strong fiel d's [H>H-c2(T- T-c)] it decreases logarithmically, only while Aslamazov-Lar kin and anomalous Maki-Thompson contributions diminish as powers of H-c2/H. [S0163-1829(98)03546-2].