Magnetic and magnetoresistive properties of sputtered permalloy thin films

The dependence of the magnetic properties, especially magnetoresistivity, of sputtered permalloy thin films on the sputtering Ar pressure is studied. The Ar pressure is varied between 0.106 and 1.06 pa. The coercivity and the electrical resistivity of permalloy films both remain stable in this pressure range. These two properties are dependent on the grain size of a permalloy film, which is independent of the Ar pressure in this pressure range. The average grain size is 10–12 nm in diameter. The magnetoresistivity δϱ decreases and the anisotropy field increases as the Ar pressure decreases. Magnetoresistivity is related to the preferred orientation of the sputtered permalloy film. The permalloy films deposited at high Ar pressures have no preferred orientation; therefore, they show high magnetoresistivity.