Maria Dolores Baró

Abstract:

Periodic ripple and nanoripple patterns are generated at the surface of amorphous steel after femtosecond pulsed laser irradiation (FSPLI). Formation of such ripples is accompanied by the emergence of a surface ferromagnetic behavior, which is not initially present in the non-irradiated amorphous steel. The occurrence of ferromagnetic properties is due to the FSPLI-induced surface devitrification of the glassy structure to form ferromagnetic (a-Fe and Fe₃C) and ferrimagnetic [(Fe,Mn)₃O₄ and Fe₂CrO₄] phases located in the ripples. The generation of magnetic structures by FSPLI turns out to be one of the fastest ways to induce magnetic patterning without the need of any shadow mask. Furthermore, the adhesion force, wettability and nanomechanical properties of the surface treated by FSPLI are also studied and compared to those of the as-cast amorphous alloy. These effects are of interest for applications (e.g., biological, magnetic recording, etc.).