IRG 1:
Nanomagnetism: Fundamental Interactions and Applications
The unifying theme of this IRG is the study of exchange and magnetostatic interactions between particles or grains in nanostructures. Understanding these interactions is a fundamental problem in magnetism and spin electronics and of technological importance in areas such as magnetic recording media, magnetoresistive sensors, and permanent-magnet materials. Since nonlocal, nonlinear, and nonequilibrium effects play important roles in nanostructures, the atomic origin of their magnetism requires relativistic quantum-mechanical solutions for very complex interfaces and boundaries.
This IRG brings a unique and powerful combination of theoretical and experimental expertise to bear on fundamental quantum and electronic-structure aspects of nanomagnets and magnetic interfaces, nanofabrication issues, and basic exchange and magnetostatic interactions.
IRG 1 Research Areas:
A. Magnetic Nanoparticles, Clusters and Nanocomposites:
This research employs recently discovered or developed methods to fabricate clusters and nanocomposites with high potential for future information-storage, permanent-magnet or other technologies. A multi-source cluster deposition system is used to prepare magnetic clusters with diameters d in the range of 4-10 nm. These clusters, which are high-anisotropy materials such as FePt or CoPt, or soft materials such as Fe, are embedded in nonmagnetic or other magnetic phases. The materials have potential as recording media at 1 terabit/in2, and high energy-product magnets. Theoretical work and simulations complement the experimental work.
Topics:
- High-Anisotropy Magnetic Nanoclusters
- Intra-Particle Exchange-Coupled Nanomagnets
- Antiferromagnetic Oxide Nanoparticles
B. Novel Patterned and Layered Magnetic Nanostructures:
This project focuses on experimental and theoretical work to understand magnetic interactions and properties in laterally patterned nanodots and multilayer heterostructures exhibiting exchange bias. In the former case, a direct, large-area patterning is achieved by laser-interference and local heating that produces structural and magnetic changes. In the latter case novel exchange coupling is observed through thin layers of an antiferromagnet, NiO. Theoretical modeling also complements this work.
Topics:
- Dynamics of Exchange-Coupled Magnetic Heterostructures
- Exchange Bias in Multilayer Heterostructures
IRG 1 Highlights
Published 2008: “Simple Models of Magnetism” by Ralph Skomski (Oxford University Press) (March 2008).
Books on Nanomagnetism 2006 (published by Springer, Berlin):
“Advanced Magnetic Nanostructures”,
edited by David Sellmyer and Ralph Skomski
“Handbook of Advanced Magnetic Materials”,
edited by Yi Liu, D. J. Sellmyer, and Daisuke Shindo
The Most Down-Loaded AIP Paper 2004 (in a Two-Month Period)
Nanotube Magnetism” (Y.C. Sui, R. Skomski, K.D. Sorge, and D.J. Sellmyer)
Journal of Physics: Condensed Matter: Top Paper 2003
“Nanomagnetics” (R. Skomski)
Selected as one of the top 50 papers ever published in the field of nanotechnology theory and modeling, and included in a reprint volume 2006.
Recent IRG 1 Research Nuggets:
Reaching a New Level of Nanostructuring: Two-Phase Clusters
Nanostructuring for High-Energy Magnets
Magnetization Reversal of Patterned Submicron-Sized Dot Arrays
IRG 1 Researchers
David Sellmyer (coordinator) - Nanofabrication, clusters (SQUID etc.)
Shireen Adenwalla - Nanofabrication, multilayers and e-beam (Neutron Scattering)
Roger Kirby - Laser patterning (MO, Fast Dynamics)
Diandra Leslie-Pelecky - Magnetic nanoparticles
Sy-Hwang Liou - Nanofabrication (SPM and MTM)
Renat Sabirianov - First principles calculations and micromagnetic modeling
Jeff Shield - Clusters and mechanical methods (TEM etc.)
Ralph Skomski - Theory of magnetic nanostructures
