Short-range order above the Curie temperature in the dynamic spin-fluctuation theory

• We study the spin correlations in ferromagnetic metals above the Curie temperature.
• We derive computational formulae for the spin correlator and correlation radius.
• The correlation radius decreases inversely with temperature over a wide interval.
• The calculated short-range order in Fe is small, in agreement with experiment.
• A considerable amount of short-range order in Fe persists up to high temperatures.

Based on the dynamic spin-fluctuation theory, we study the spin-density correlations in the ferromagnetic metals. We obtain computational formulae for the correlation function and correlation radius in different approximations of the theory. Using these formulae, we calculate the magnetic short-range order above the Curie temperature in bcc Fe. Results of the calculation confirm our theoretical prediction that the inverse correlation radius increases linearly with temperature for T sufficiently large. The calculated short-range order is small but sufficient to correctly describe neutron scattering experiments. A considerable amount of the short-range order is shown to persist up to temperatures much higher than the Curie temperature.