MAGNETIC-INTERACTIONS IN FE FILMS SPUTTERED ON NANOCHANNEL ALUMINA

We present in this work a study of the magnetic interactions observed in Fe films sputtered onto the surface of commercial porous nanochanne l alumina. These films, which grow in a ''network-like'' structure, ha ve been characterized by delta M plots, magnetic viscosity and activat ion volume as a function of film thickness (5 nm less than or equal to phi less than or equal to 100 nm) and substrate pore size (20 nm, 100 nm and 200 nm average diameter). We have found a maximum in the reman ent coercivity and a minimum in the interparticle interaction for a fi lm thickness phi similar to 20 ram for the three substrates. The behav ior of the magnetic viscosity and the activation volume on the other h and is dependent on the pore size. We have interpreted our results in terms of the different porosity of the substrates. As the porosity is smaller for the substrates with smaller holes, the continuous film beh avior is approached first because the pores fail in more rapidly.