Nov 12, 2009
Nanowriter manipulates magnetic nanoparticles for high-density data storage
One promising concept for increasing the data storage density of hard drives is to use individual magnetic nanoparticles to represent single bits of information. However, a major issue has to be solved: how to control the density of nanometre-sized particles on a surface and simultaneously regulate their size. Together, two teams of researchers from Orléans and Marcoussis in France are working on a solution and have demonstrated that focused ion beam irradiation is well suited to the task of tailoring the morphology and density of magnetic nanoparticle assemblies.
In a recent study, which was published in the journal Nanotechnology, the groups used a focused ion beam as a nanowriter to modify the size and the density of an array of cobalt-platinum nanoparticles prepared via molecular beam deposition. This technique allows the researchers to fabricate assemblies of monodisperse nanoparticles with predictable magnetic properties.
However, as with most nanoparticle fabrication techniques based on atom deposition methods, the size and density of particles are interdependent. José Penuelas and co-workers showed that the dispersion and morphology of as-grown self-organized nanoparticles can be tuned via the post-irradiation dose of a low-energy ion beam without changing the structure of the material.
The combined use of ultimate fabrication and patterning techniques provides a new way to obtain ultra small particles (in the 1–3 nm range) with tunable density. The main advantage of the focused ion beam approach is the ability to pattern the size and density of nanoparticles in a local way (over areas ranging from some tens of nanometres to several millimetres). These findings open the door to building new nanoscale model systems.
The results of the study have strong consequences for supported nanoparticle systems with properties that are related to feature size and interparticle spacing.
About the author
The preparation and characterization of nanoparticles was performed at the Centre de Recherche sur la Matière Divisée (CNRS, University of Orléans, France) and the focused ion beam irradiation at the Laboratory for Photonics and Nanostructures (CNRS Marcoussis, France). Dr José Penuelas is now associate professor at Lyon Institute of Nanotechnology (Ecole Centrale de Lyon, Université de Lyon, France) and he is currently working on oxide and semiconductor heterostructures for nano-electronic and photonic applications. Dr Caroline Andreazza is leader of the Aggregates and Nanostructures Group with Dr Pascal Andreazza, associate professor at Orléans University, and their work focuses on semiconductor nanowires and magnetic nanoparticles. Dr Abdelkarim Ouerghi is a researcher at Laboratoire de Photonique et Nanostructures, CNRS Marcoussis, and he is currently working on graphene nanostructures. Dr Jacques Gierak and Eric Bourhis both from LPN, CNRS, are managing and developing the "Ultimately Focused Ion Beam" research activities at LPN.