Multiferroic properties of Bi0.8La0.2FeO3/CoFe2O4 multilayer thin films

Bi0.8La0.2FeO3/CoFe2O4 (BLFO/CFO) multilayer thin films (totally 20 layers BLFO and 19 layers CFO) were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. X-ray diffraction and transmission electron microscope measurements show that the films are polycrystalline and consisted of multilayered structure. Ferroelectric hysteresis loops with remnant polarization and saturated polarization of 4.2 and 13.3 μC/cm2, respectively, were observed. On the other hand, the films show well-shaped magnetization hysteresis loops with saturated and remnant magnetization of 34.7 and 11.4 emu/cm3, respectively, which are significantly larger than pure BLFO thin films deposited under the same conditions. These results indicate that constructing epitaxial superlattice might be a promising way to fabricate multiferroics with improved properties.