Realization of magnetization reversal at a nanoscale by employing an electrical field is extremely important for the development of various spintronic devices.Several ways to control the magnetization by modulating ferroelectric/ferromagnetic coupling,interfacial effects,carrier concentration and the orbital occupation of electrons etc are mostly achieved at low temperatures and usually require the assistance of a magnetic field.Recently,electrical field control of magnetic moment and coercive field at room temperature has been reported in single phase oxides by controlling ion migrations.In this talk,we present our progress on controlling magnetic domain structure in ferfite thin films at a nanoscale by applying an electric field to induce the ions migration at room temperature,without the assistance of a magnetic field.It is found that a moderate concentration of oxygen vacancies in the films is required to enable the magnetization reversal.First-principles calculations revealed that the magnetization reversal is induced by the reversible migration of Co2+ ions between Fe vacancies that modulated the preferred magnetic moment direction.This result is important for realizing low-power consumption,high density and nonvolatile "electric-write,magnetic-read"memories.