Dominance of the spin-wave contribution to the magnetic phase transition in FeRh

Density functional calculations are performed to investigate the phase transition in FeRh alloy. The effective exchange coupling, the critical temperature of magnetic phase transition, and the adiabatic spin wave spectrum have been obtained. Different contributions to the free energy of different phases are estimated. It has been found that the antiferro-ferromagnetic transition in FeRh occurs mostly due to the spin wave excitations.