Tinkering with magnetism
doi:10.1038/nindia.2009.86 Published online 23 March 2009
An international research team has stumbled upon a new way to tinker with iron atoms and shape their magnetic properties1.
The researchers assembled iron and benzenedicarboxylic acid molecules (terephthalate acid or TPA) on copper surface. This resulted in ordered arrays of iron atoms on a nano-sized square grid. Then they switched the magnetization direction of iron atoms through oxygen adsorption, opening up a way to control magnetic property similar to that used in metallic thin films.
Such atomic-scale structures have the potential to be harnessed for quantum computing.
Controlling magnetic anisotropy is important in the development of molecule-metal interfaces for magnetic applications at the single-molecule and extended-film level. Theoretically, it was possible to reverse magnetic anisotropy in metal organic complexes by exploiting oxidation processes. The researchers made self-assembly of iron atoms on a non-magnetic copper surface and added TPA. The iron-TPA complexes on copper formed mono- and bi-nuclear network structures on 1.5 nm square grids. Each iron atom was attached to four TPA through carboxylate bonds.
On exposure to oxygen, selective adsorption of oxygen took place close to iron on-top positions. This changed the electronic structure and magnetic properties of iron atoms. The co-deposition of transition-metal ions and organic compounds on crystalline surfaces offers the potential to design supramolecular grids with programmable structural and chemical features.
The findings are significant as modifications of the particle size, shape, and coupling with the substrate, making nano-sized systems are attractive for basic investigations as well as for miniature data-storage applications. Atomic scale magnetic structures are also of great scientific interest because they exhibit intriguing quantum effects.
The authors of this work are from: Centre d'Investigacions en Nanociència i Nanotecnologia (ICN-CSIC)and Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Max-Planck-Institut für Festkörperforschung, Stuttgart; Physik-Department, Technische Universität München and Physik-Department E20, Technische Universität München, Garching, Germany; Department of Applied Physics, Chalmers University of Technology, 41296 Göteborg, Sweden, Department of Chemistry, Utrecht University, The Netherlands; Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India; European Synchrotron Radiation Facility, Grenoble; and Institut de Minéralogie et de Physique des Milieux Condensé, Université Pierre et Marie Curie, Paris, France.
- Gamberdella, P. et al. Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface. Nat. Mater. 8, 189-193 (2009) | Article |