Magnetic and structural properties of laser-ablated planar and cylindrical co thin films

摘要

Planar and cylindrical Co thin films have been obtained by pulsed laser ablation. X-ray diffractograms have shown no crystalline structure for the as-deposited samples, while the 450 deg C annealed samples exhibit Co fcc crystalline peaks. The Scanning Tunnelling Microscopy has revealed a small increase of the surface roughness for the annealed films. The Hall effect has been used to determine the value of the spontaneous magnetization, M_s, at room temperature; M_s approx approx 14 kgauss for the as-deposited sample and M_s approx approx 17.6 kgauss for the 450 deg C annealed sample. From transverse magnetooptic Kerr effect, it has been found that the as-deposited samples exhibit magnetic bistability, with a coercive field, H_c, approx approx 6 Oe. The annealed samples also show a bistable behavior until the annealing temperature is 450 deg C. Besides, it has been observed an increase of H_c up to approx approx 50 Oe, when the annealing temperature increases. The vibrating sample magnetometry has confirmed these results, showing that the magnetization participating in the magnetooptic effect for these low fields is the total spontaneous magnetization of these samples. Moreover, the cylindrical films exhibit magnetoelastic behavior when they are subjected to angular deformation. It has been found that the saturation magnetostriction constant is negative.