Coexistence of ferro- and antiferromagnetism — A spin fluctuation theory

The coexistence of and transition between ferro- and antiferromagnetism in itinerant electron system are investigated by extending the spin fluctuation theory of ferromagnetic metals by Usami and Moriya. Calculation is made on a model density of states, which simulates the one for d metals with a body centered cubic crystal structure. The result shows that the wavevector-dependent susceptibility χ_q has a two peaks at q = 0 and q = Q for the suitable choice of parameters and the coexistence is realized when the amplitude of spin fluctuation takes a proper value. Paramagnetic susceptibility of this system is also discussed.