Jul 1, 2010
Tailoring the magnetization processes of iron nanowires
Magnetic nanowires with different morphological features can be fabricated through a wide variety of procedures. Popular techniques include deposition on self-organized templates and the artificial structuring of thin films by lithography. Magnetization processes have been widely studied by many groups and depend not just on the shape, dimensions and intrinsic properties of the material, but also on many extrinsic factors. This means that structures are extremely sensitive to the specific characteristics of the fabrication route employed and, in practice, it can be difficult to provide a general description of their magnetic behaviour. This is a drawback for the technological applications of magnetic nanowires, which require well controlled magnetization processes, independent of the imperfections introduced during fabrication.
To investigate the topic in more detail, scientists from the Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC) and the Technical University of Madrid have used a homemade Pulsed Laser Deposition system to produce high-quality epitaxial Au(001)/Fe(001)/Mg(001) thin films with very sharp and flat Au/Fe and Fe/MgO interfaces.
The team has fabricated arrays of nanowires in these films, 100 nm to 1000 nm wide, through three different routes, Focused Ion Beam and Electron Beam lithography with either positive or negative resist. Here, the magnetization processes of the nanowires were essentially controlled by their shape and dimensions and by the intrinsic magnetic parameters of iron, with negligible influence of the imperfections inherent to the thin-film deposition and to the three lithography techniques.
The ability to achieve such high-quality nanostructures offers a unique opportunity to study them as model systems and to explain their magnetization reversal by means of a simple analytical approach, with very good agreement between the calculations and the experimental data.
More information can be found in the journal Nanotechnology.
About the author
The team is involved in the research of magnetization processes of artificial nanostructures fabricated in thin films by different lithography techniques. Although team members collaborate in all of the research tasks to some extent, their interests are focused in different areas. Dr Elvira Paz is with the Nanostructures and Surfaces Department of the Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC); she has optimized the lithography procedures for the fabrication of nanowires and carried out structural and magnetic characterization of the arrays. Dr Francisco Javier Palomares is a staff researcher in the same department who specializes in deposition techniques and chemical and structural characterization of low dimensional structures. Dr Jesús M González (also at the ICMM-CSIC) and Prof. Federico Cebollada (POEMMA-Technical University of Madrid) have a well established background in magnetism. Dr Felipe García Sánchez has been mostly involved in magnetic simulation, and he is currently working with the group of Dr Hertel (Magsim) at Institut für Festkörperforschung in Jülich, Germany.