  An accurate prediction of atomic diffusion in Fe alloys is challenging due to
thermal magnetic excitations and magnetic transitions. We propose an effcient
approach to address these properties via Monte Carlo simulation, using
ab-initio based effective interaction models. The temperature evolution of
self- and Cu diffusion coeffcients in alpha-iron are successfully predicted,
particularly the diffusion acceleration around the Curie point, which requires
a quantum treatment of spins. We point out a dominance of magnetic disorder
over chemical effects on diffusion in the very dilute systems.
