Micro-Structure and Magnetic Properties of Perpendicular Magnetized Co-CoO Sputtered Films

The electrical resistivity of reactive RF sputtered Co-CoO films increases and the temperature coefficient of resistivity decreases with the formation of CoO. For films with a saturation magnetization (Ms) of more than 670 emu/cm³, the resistivity decreases irreversibly above 370 K by deoxidization. For films with an Ms of less than 470 emu/cm³, the resistivity increases irreversibly above 420 K. After the irreversible increase in resistivity, the coercivity (Hc) and squareness ratio of the hysteresis loop perpendicular to the film plane increase, and the Hc parallel to the film plane decreases.