A huge maximum in the temperature dependence of the susceptibility of FeSi

The temperature dependence of the susceptibility of the narrow-gap semiconductor FeSi is calculated by taking into account the effect of the Fermi distribution function and that of the spin fluctuations based on the Ginzburg-Landau theory. The temperature dependencies of the Landau parameters are estimated by using the calculated density-of-states curve and the Fermi distribution function. By the Gaussian approximation, the mean square amplitude of the spin fluctuations is obtained self-consistently with the susceptibility. The observed huge maximum in the temperature dependence of the susceptibility is obtained