Ferroelectricity and antiferromagnetism in multiferroic materials explained by photonic tunneling model

ABSTRACT Considering a photon field from its constituent electrons and ions, a photon correlation theory for ferroelectrics and antiferromagnetism is proposed. We calculate the spontaneous polarization which originates from a certain alignments of photon field in correlation with the specific phonon mode. Using the microscopic Hamiltonian we obtain the ferroelectric transition temperature, Tc and the antiferromagnetic transition temperature, TN in multiferroic materials. Tc and TN are given by same formula except different wavevector dependence originated from geometric difference between ferroelectrics and antiferromagnetism in multiferroics. The correlation between magnetic field and electric field on ferroelectrics and antiferromagnetism is considered to obtain the spontaneous polarization in good correspondence with experimental data.