Influence of nature of the substrate on the soft magnetic properties of pulsed laser ablated-deposited amorphous Co

Amorphous Co films, ∼270 nm thick, were prepared by pulsed laser ablation-deposition. Substrates of glass, monocrystalline Si(1 1 1), copper and tungsten were used. The surface morphology of the films, studied by means of scanning tunneling microscopy, STM, as well as the coercive field, Hc, and room temperature spontaneous magnetization, Ms, was determined. The Ms values were approximately the same for all films independent of the substrate; on the contrary, significant variation of Hc was found for the films grown on different substrates. The lowest coercive field, Hc∼1.2 Oe, corresponds to the samples grown on glass and Hc∼1.6 Oe to the films deposited over Si(1 1 1) substrates, whereas Hc∼2.2 and 5 Oe were measured for the samples deposited over tungsten and copper substrates, respectively. The STM studies allowed us to correlate the different magnetic softness of the films--from both magneto-optical transverse Kerr effect and vibrating sample magnetometry--with their surface morphology