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November 1, 2005 NSLS 2005 Annual Users’ Meeting WorkshopNanomagnetism: Materials and ProbesThe connection between magnetism and nanoscience is clear: the nanometer is the natural length scale of magnetism, as it characterizes the domain wall. Unanticipated phenomena occur when the materials' structural scale coincides with the magnetic length scale. To support research into nanomagnetism, recent advances in materials synthesis and nanofabrication technology have made it possible to create a wide range of nanomagnetic systems with unprecedented precision. These novel magnetic systems are used as model systems for testing longstanding theories in magnetism, as well as for exploring new device concepts and applications. In parallel, synchrotron radiation, with its unique polarization properties, tunability, and time structure, has become an indispensable tool for the study of magnetism and magnetic materials.
The 2005 NSLS Users' Meeting Workshop, "Nanomagnetism: Materials and Probes," provided an overview of the latest synchrotron characterization techniques as well as introduced new materials concepts for magnetic materials. The workshop was jointly sponsored by the Brookhaven National Laboratory (BNL) Center for Functional Nanomaterials, a new U.S. Department of Energy (DOE) nanoscience user facility. Presentations were delivered by seven experts in the application of synchrotron radiation to magnetic materials, and in the synthesis and application of magnetic nanomaterials, with the goal of presenting an up-to-date snapshot of the forefront issues in nanomagnetism. Daniel Haskel of the Advanced Photon Source at Argonne National Laboratory inaugurated the workshop with a presentation on recent synchrotron characterization advances that elucidate the role surfaces and interfaces at play in the overall magnetic response, especially in thin-film layered systems. Professor J. M. D. Coey of Trinity College in Dublin, Ireland, followed with surprising but well-documented results that systems with nominally no d-electrons, such as HfO2 and RhO2, exhibit ferromagnetism under certain conditions. The results are currently attributed to the defect state of the material.
Continuing the focus on novel magnetic materials, Distinguished Professor Myriam P. Sarachik of City College-CUNY presented new results on molecular magnets or single-molecule magnets. These systems, which bridge the classical and the quantum worlds, hold potential as quantum computation materials (qubits) and exhibit clear quantum-mechanical tunneling signals under the influence of magnetic fields. Professor Sara A. Majetich of Carnegie Mellon University discussed recent results obtained from highly uniform monodisperse arrays of ferromagnetic Fe, Co, and FePt nanoparticles (Figure 1). The competition between dipolar and anisotropy energies in these systems creates spin-glass-like mictomagnetic behavior, as revealed by small-angle x-ray scattering and small-angle neutron scattering. Glenn A. Held of the IBM T. J. Watson Research Center in Yorktown Heights, New York, presented an overview of magnetic ferrite nanoparticles encapsulated by biologically active molecules to create bio-functionalized entities for monitoring and influencing cellular processes. The workshop concluded with two presentations on advanced synchrotron techniques for magnetism characterization. Dario Arena of the NSLS discussed new techniques that probe the dynamics of magnetization precession in the time domain, with element specificity. In this work, time-resolved magnetic circular dichroism in a pump-probe architecture was employed to examine the moment response in permalloy-based systems. Andreas Scholl of Lawrence Berkeley National Laboratory described the application of ultrafast x-ray pulses (picosecond to femtosecond) to image magnetic dynamics with high spatial resolution. As an example of the technique, real-time movies with associated analyses of the precessional dynamics of magnetic vortices were presented. ACKNOWLEDGEMENTS FOR MORE INFORMATION |
The National Synchrotron Light Source at Brookhaven National Laboratory in New York, is a national user research
facility funded by the U.S. Department of Energy's Office of Basic Energy Science. The NSLS operates two electron
storage rings: an X-Ray ring and a Vacuum UltraViolet (VUV) ring which provide intense light spanning the electromagnetic
spectrum from the infrared through x-rays. Each year over 2300 scientists from universities, industries and government
labs perform research at the NSLS.
