Abstract
Nanocomposite permanent magnets made of hard and soft magnetic nanoparticles are important nanostructured materials. They, however, present substantial theoretical challenges due to the need to treat the electronic interactions quantum-mechanically whilst dealing with a large number of atoms. In this presentation, we show a direct quantum mechanical simulation of magnetic nano-structures made of spherical L10-FePt nanoparticles, with diameter within 2.5-5 nm, embedded in an fct-FePt random alloy. The calculation is performed using the locally self-consistent multiple scattering (LSMS) method, a linear scaling ab initii method capable of treating tens of thousands of atoms. We found that there exists a screening region below the surface of each nanoparticle. This screening region essentially screens out the effect of the external random alloy to keep the physical properties of the interior region unchanged from the bulk of L10-FePt. Interestingly, the depth of this screening region is around 4 Å and is independent of the size of the nanoparticles we have investigated. We will discuss the formation of this screening region and the effect of the external random alloy on the electronic and magnetic structure of the nanoparticles.
Original language | English |
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Pages (from-to) | 3103-3105 |
Number of pages | 3 |
Journal | IEEE Transactions on Magnetics |
Volume | 43 |
Issue number | 6 |
DOIs | |
State | Published - Jun 2007 |
Funding
This work was supported in part by the National Science Foundation under Cooperative Agreement No. SCI-0456541, the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering under Contract No. DE-AC05-00OR22725 with UT-Battelle LLC., and US DoD/MURI Grant N00014-05-1-0497. Y. W. would like to thank fruitful discussion with Prof. S. A. Majetich and Dr. Yi Ding. Calculations presented in this paper were performed at Pittsburgh Supercomputing Center and at the Center for Computational Science (CCS) at ORNL.
Keywords
- Ab initio
- FePt
- LSMS method
- Nanoparticle