Raman Light Scattering on Multiferroics

Ferroelectrics and magnets are among the most important materials for technological applications to date like, ac magnetic field sensors, oscillators, filters, and computer hard drives. Magnetism is due to the spin of electrons in partially filled d shells, while ferroelectric is due to off-center structural distortions. These two phenomena can coexist in a certain class of materials called multiferroics. Beside the possible coexistence of ferroelectricity and magnetism, a coupling between magnetic and electric order parameters (magnetoelectric effect) have been observed in some materials called multiferroics. The main objective of this thesis is to investigate the magnetic and ferroelectric phase transitions temperatures which are seen by other techniques and to examine the existence of structural phase transitions from Pbam (paraelectric phase) to Pb21m (ferroelectric phase) of the aforementioned systems by Raman inelastic light scattering