A magneto-optical device (MOD) with optically induced magnetization for use in magnetic field sensors as a magnetic element pinning a magnetization in a preferred direction of a ferromagnetic layer as well as a magnetic memory cell for magneto-optical recording. The MOD comprises the Mg—Mg—Co ferrite film deposited on a magnesium oxide (MgO) substrate. The ferrite film is illuminated at room temperature with a circularly polarized light (CPL) in a static magnetic H-field (about of 3 kOe) normal to the illuminated ferrite film surface. At certain (“writing”) combinations of H, sigma (CPL helicity), the long-lived optically induced magnetization with a unidirectional anisotropy, stable to a conventional demagnetization occurs. For readout of information, conventional magnetoresistive sensors and MFM can be used. To erase information, the ferrite film should be illuminated with two field-light combinations, other than “writing”, or annealed at temperature higher than 530 degrees C.