Materials World Network: Self-assembled Nanocomposite Magnetoelectric Thin Films Nian Sun, Northeastern University, DMR Intellectual Merit:Fig. 1 Schematic of the stress- mediated magnetoelectric effect. Fig. 2 High resolution TEM image of core shell nanowire arrays. The magnetoelectric (ME) effect is the variation of dielectric polarization under an applied magnetic field, or the presence of an induced magnetization under an applied electric field through a stress- mediated interaction, as shown in Fig. 1. This effect enables effective energy conversion between electric and magnetic fields, which leads to many novel devices. Strong ME effects have been realized in bulk multiferroic materials. However, it has been challenging in achieving strong ME coupling in low-dimensional ME composite materials

Fig. 3 Ferrite/PZT Core-shell nanowires. Fig. 4 Magnetic field induced electrical polarization change. The focus of this proposal is therefore to investigate novel low-dimensional ME nanocomposite materials with strong ME effect. We have recently developed a novel synthesis method for core-shell ME nanowire arrays. Fig. 2 shows the images of NiFe2O4 – Pb(Zr,Ti)O3 (PZT) core-shell ME composite nanowire arrays in nanoporous alumina templates. Individual core-shell nanowires with a high aspect ratio were extracted and shown in Fig. 3. This work was recently published in Applied Physics Letters, which was also selected for the April 23, 2007 issue of Virtual Journal of Nanoscale Science & Technology.the April 23, 2007 issue of Virtual Journal of Nanoscale Science & Technology Materials World Network: Self-assembled Nanocomposite Magnetoelectric Thin Films Nian Sun, Northeastern University, DMR

In addition, we have developed a novel simplified sol-gel synthesis method for ME nanocomposite thin films with very fine grain size in the range of 5~10 nm. The fine grain size in the ME nanocomposite films results in significantly reduced leakage current and strong ME effect. This was demonstrated in a CoFe2O4-PZT nanocomposite film as shown in Fig. 4, in which the P-E hysteresis loop is changed by magnetic field. Materials World Network: Self-assembled Nanocomposite Magnetoelectric Thin Films Nian Sun, Northeastern University, DMR

Materials World Network: Self-assembled Nanocomposite Magnetoelectric Thin Films Nian Sun, Northeastern University, DMR Fig. 5 Center for Microwave Magnetic Materials and Integrated Circuits, Northeastern University, MA. Fig. 6 National Laboratory of Solid State Microstructures at Nanjing University, China. Fig. 7 Virginia Tech. Fig. 8 National Physical Laboratory, UK. Fig. 9 Museum of Science, Boston. Broader Impacts: Synergy: This NSF award allows us to establish an active collaboration between the Center for Microwave Magnetic Materials and Integrated Circuits at Northeastern University, MA (Fig. 5), and the National Laboratory of Solid State Microstructures (LSSMS, Fig. 6) at Nanjing University, China. The co-PI Dr. J.M. Liu visited Center for Microwave Magnetic Materials and Integrated Circuits at Northeastern University in November ~ December, The PI N.X. Sun will also visit the LSSMS at Nanjing University in March Two papers have been published with this NSF award.

Materials World Network: Self-assembled Nanocomposite Magnetoelectric Thin Films Nian Sun, Northeastern University, DMR Undergraduate and Graduate Students Education and Participation of Underrepresented Groups: The PI has been putting great emphases on educating underrepresented students. There are 3 minority African-American students in the PI’s group supported by this NSF award, including two graduate students: Carl Pettiford, Ogheneyunm Obi (female), and one research experience for undergraduates (REU) participant Stephen Stoute. In addition, several other minority or female research experience for teachers (RET) and REU participants worked in the PI’s labs during 2006 and 2007 summer semester under this NSF award. More information is available at: Magic of Magnetism for the Museum of Science, Boston: Besides graduate, undergraduate, and K~12 education, the PI is in the process of developing an interactive Magic of Magnetism program for the Museum of Science (MoS) Boston, together with the Cahners Computer Place at the MoS. Each year, more than 1,600,000 visitors visit the MoS; about one third of these visitors are students. The purpose of this interactive Magic of Magnetism program at the Museum of Science (MoS) is for entertaining as well as informally educating the general public on the topics of magnetism and magnetic materials, and their involvement in our everyday