Producing Three Dimensional Nanostructured Magnetic Materials for Novel Magnetic Devices

Abstract

The public reportmg burd en for th1s collection of mform ation is estimated to average 1 hour per response. includmg the tim e for rev>ewing instruct>ons. searclhing exi sting data so urces. gathering and mmnta1mng the data needed . and co mpleting and rev1ew 1 ng the collection of 1nforma t1 on. Send co mments regarding th1s burden est1m ate or any other aspect o fth1s collection of mformat1on . 1nclud1 ng suggesti ons for reduc1 ng the burden. to the Department of De fense. ExecutiV e Serv1ce D>rectorate (0704 -0 188) Respo ndents should be aware that notwithstanding any other prov1 s1 on of law. no person shall be sub;ect to any penalty for falling to comply w1th a collect> on of 1 nform at1on if 1 t does not display a currently v alid OMB co ntrol number PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY)12. REPORT TYPE 3. DATES COVERED (From-To) SPONSOR/MONITOR'S REPORTArlington, VA 22203 NUMBER(S)AFRL-OSR-VA-TR-2012-0387 DISTRIBUTION/AVAILABILITY STATEMENT A SUPPLEMENTARY NOTES ABSTRACTWe have produced large sized 3D magnetic nanocomposites using a current activated pressure assisted densification (CAP AD). We were successful in producing dense nanocrystalline ( < 1 00 nm average grain size) materials based on iron oxides (ferrites ), rare earth oxides and silicon We have demonstrated magnetic coupling leading to exchange bias in large nanocrystalline iron oxides. Additionally we can orient the magnetically coupled grains causing their magnetic properties to be highly anisotropic. These materials have promising applications in magneto-resistance based devices as well as permanent magnets. The rare earth oxides are transparent to visible light and cause very high Faraday rotations. The Verdet constant of these nanocrystalline materials is more than twice that of the state of the art Faraday rotation materials. We also used the CAP A D technique to show that the thermal conductivity in of polycrystalline silicon can be controlled using nanostructure. 1S. SUBJECT TERMS