Ferrimagnetic thin films prepared by pulsed laser deposition

Thin films, with thickness ranging from 25 nm up to 1.5 μm, of well-known ferrimagnetic materials such as NiFe 2 O 4 , CoFe 2 O 4 , Ni 0.5 Zn 0.5 Fe 2 O 4 , and BaFe 12 O 19 have been prepared by PLD. Films made at low substrate temperature (T < 500°C) are amorphous, but can crystallize by post-annealing in air in the temperature range 500-800°C. Films deposited at temperature between 500 and 800°C are polycrystalline, the grain size (from 50 nm to 1 μm) and surface roughness (1-100 nm) depending upon deposition parameters. The polycrystalline films are ferrimagnetic with a saturation magnetization close to the bulk value (J s = 0.3 T for Ni-ferrites). Spinel films are isotropic as deduced from torque balance measurements. Coercivities are rather high for the spinel films (up to 500 Oe for Ni-ferrite) and even higher for the hexaferrites (3 kOe).