Multiferroic properties in transition metals doped La sub(2)Ti sub(2)O sub(7) ceramics

A series of nominal componential La sub(2)Ti sub(1.97)T sub( 0.03)O sub(7) (T = Co, Fe, Mn, Cr) ceramics (LTO-T) are prepared by a conventional sol-gel method. X-ray diffraction analysis reveals that all of the samples except LTO-Cr ceramics are pure with no trace of second phase. Room temperature (RT) ferromagnetic and ferroelectric behaviors are confirmed experimentally for transition metals doped La sub(2)Ti sub(2)O sub(7). Especially for the Co doped samples, saturated magnetization and enhanced electric property are observed. These results suggest that doped with transition metals (TM) helps to change La sub(2)Ti sub(2)O sub(7) to RT multiferroic materials. The temperature dependant magnetic behavior shows complex magnetic interactions including ferromagnetic, antiferromagnetic, and paramagnetic. The ferromagnetism can be explained as effective exchange coupling interaction between oxygen vacancies and TM 3d spins.