Existence of quasi-ferroelectricity in CoFe2O4 ferromagnetic films induced by Li+-Al3+ codopant.

Single phase multiferroics are rare in nature, because ferroelectric and ferromagnetic orderings require empty d -orbits and filled d -orbits, respectively. Here we demonstrate that ferroelectricity can be induced by ion-pair doping in ferromagnetic oxide such as ferrites with filled d -orbits. Our study shows that a new kind of room temperature multiferroic can be achieved in single phase thin films of CoFe 2 O 4 with Li + -Al 3+ pair substitution of Co 2+ along 〈110〉 direction. A ferroelectric domain mechanism related to ion-pairs in co-doped thin films was revealed. Importantly, a new way for fabricating single phase multiferroic materials is provided in the present study. [ABSTRACT FROM AUTHOR]