Ion doping effects on the properties of multiferroic BiFeO3 nanoparticles

The influence of ion doping on the ferromagnetic and ferroelectric properties in multiferroic nanoparticles is studied based on the modified Heisenberg and transverse Ising model. Using a Green's function technique we have calculated static and dynamic properties in dependence of temperature, particle size, and defects. It is demonstrated that the magnetization M, the polarization P, the critical temperatures TN and TC, the spin-wave energies Em and Ee, and their damping are very sensitive to the exchange interaction constants in the defect shell(s) A1d and Jd. We have obtained that the magnetization M and the polarization P can be enhanced in BiFeO3 nanoparticles due to different defects.