  This letter reports our experimental results on magnetic-field-induced
aftereffects in solution derived Bi4Fe2TiO12 film, in which e' decreases as
much as 600 times after treated in a 5T magnetic field as that of the pristine
one. The phenomena are explained by an unusual spin-orbital coupling in film,
where strong magnetic field provides drive force for spin polarized electrons
of electrode to enter film, so as to form a ferromagnetic orbital state,
increase the relaxation time of defect dipoles and then produce giant
magnetodielectric effects. This process is reversible just by applying a
opposite 0.5T magnetic field. Our findings have potential applications on
magnetic fabrication of nanopatterns somehow to evade nanohazard, as well as on
integraged phononic or photonic crystals on chip.
