Abstract
We report on the synthesis and characterization of thin M-type barium hexaferrite (BaFe(12)O(19)or BaM) films on sapphire (0001) substrates by RF magnetron sputtering. Single layers of 150 nm, 200 nm (S-200), 400 nm (S-400), 600 nm, and 700 nm were fabricated. Multilayered technique with inner-layer annealing was employed to fabricate the 400 nm (M-400) BaM films. The thickness dependence of the magnetic, structural, elemental analysis, and surface morphological properties of the BaM films has been investigated using VSM, XRD, EDX, and SEM, respectively. For the M400BaM films, excellent magnetic properties with high values of out-of-plane coercivity (H-c & x2534; = 3.1 KOe) and squareness (S-& x2534; = 0.9) were obtained. The surface morphology of the M(400)shows a platelet-like grains, which have theirc-axis orientation in the out-of-plane direction. The magnetic properties and XRD data of the S(200)films and M(400)were about the same. For the single S-400, S-600, and S(700)films, the magnetic properties have been reduced due to the excess oxygen concentration and the exchange interactions, the stress relaxation of the lattice constant, and the formation of the acicular grains. The acicular grains of the S(400)films favor theirc-axis aligned in the in-plane direction.