High Anisotropy Magnetic Nanoparticles and Nanocomposites G.C Hadjipanayis, University of Delaware

1. High Anisotropy Magnetic Nanoparticles and Nanocomposites G.C Hadjipanayis, University of Delaware Email: hadji@udel.edu, Tel: (302)-831-2736 Figure 2: (a) Velocity contours (m/s) and (b) monomer mass fraction contours in the gun for multiple inlets of carrier gas. Fig. 1. Schematic illustration of the plasma-gas-condensation cluster gun system. Fig. 4: Typical TEM micrograph showing squared FePt nanoparticles with rounded edges. Fig. 3. Cubic shape Co nanoparticles made by the cluster gun. NSF MET DMR-0302544 • Objectives • to obtain high anisotropy magnetic nanoparticles and nanocomposites. • to study finite-size effects on their magnetic, structural and microstructural properties. • to artificially prepare special microstructures for application in high density magnetic recording and high performance magnets. Second chamber Research Highlights • Figure 1 shows the upgraded cluster gun. A second processing chamber allows us to separate the cluster growth region from the particle processing region (particle size selection, in-situ heat treatment, etc.) and therefore obtain particles with more controlled size and size distribution, and crystal structure. • Theoretical simulation and modeling of the particles flow greatly helped the design of the cluster gun. (shown in Fig.2) • Beside the spherical particles, we have successfully fabricated particles with uniform cubic shape by both the cluster gun (Fig. 3) and by chemical synthesis (Fig. 4). To our knowledge, it is the first time researchers have reported the synthesis of such uniform cubic particles using the sputtering technique.

2. High Anisotropy Magnetic Nanoparticles and Nanocomposites G.C Hadjipanayis, University of Delaware Email: hadji@udel.edu, Tel: (302)-831-2736 Figure 5. Mike Bonder demonstrated the superconductivity with 9th graders from the local high school Figure 6. Deasha Barret who is constructing electronic as part of the Summer internship program. NSF MET DMR-0302544 • Significance of the Results • Magnetic nanoparticles fabricated by the cluster gun with desired size, shape, and phase are ideal systems for both scientific and technological investigations. • FePt nanoparticles are potential candidates for future Terabit/in2 recording media. • Cubic shape particles are highly desirable for thin film media with preferred orientation and a higher packing density. • Future Plans • Fabricate nanoparticles with different size and shape and study the effect of size/shape on the intrinsic magnetic properties (Ku, Ms, Tc), phase transformation(fcc to L10), and interface interactions. • Fabricate nanocomposite materials (soft/hard, soft/magnetostrictive) for applications in permanent magnets, in magnetic actuators, and in high density magnetic recording media. Outreach • The NSF funding provides for summer support for 1-2 undergraduate and high school students each summer through the REU and departmental internship programs, respectively. Every spring 20-50 high school students and science teachers participate in the annual open-house where participants take part in lab demonstrations as well as get to tour the experimental facilities. Students work closely with the members of the lab to introduce them to cutting edge magnetics research. These experiences early in their education foster interest in research and further studies in Physics. • In addition to the summer internships the Magnetics lab also maintains a scanning electron microscope at the charter school of Wilmington where students get hands on access to advanced experimental techniques in conjunction with their science classes. Personnel • High school student(s) W. Vega-Brown, R. sherriff, D. Safranski • Undergraduate student(s) P. Hanson, D. Gallo, J. Justison, J. Danberg • Graduate students H.L.Wang, P. Liu, L. Colak • Exchange Student S. Ziesche (from Dresden, Germany) • Postdoctoral scientists Y. Huang,