Ba ferrite films with large saturation magnetization and high coercivity prepared by low-temperature sputter deposition

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Abstract
Ba ferrite films were deposited in a mixture of Xe, Ar, and O2 by using facing targets sputtering apparatus with sintered targets of Fe-excessive BaM ferrite. By using Xe as sputtering gas, the bombardment of energetic Ar atoms recoiled from target to film surface was sufficiently suppressed and Fe content in Ba ferrite crystallites was significantly increased. It was found that the segregation of spinel crystallites among BaM ones were not observed and these BaM crystallites revealed the excellent c-axis orientation normal to film plane and clear perpendicular magnetic anisotropy. At substrate temperature Ts of 600 °C, saturation magnetization 4πMs of 5.1 kG, which is larger than that of BaM ferrite single crystal, and perpendicular coercivity Hc⊥ of 2.4 kOe were obtained. BaM ferrite films composed of well c-axis oriented crystallites with large perpendicular magnetic anisotropy constant, large saturation magnetization 4πMs of 4.7 kG and high perpendicular coercivity Hc⊥ of 2.4 kOe were obtained at substrate temperature Ts as low as 475 °C.