Gas-phase prepared directly ordered FePt nanoparticles were shown to align with in situ magnetic fields. As shown by magnetic and x-ray diffraction data, a 3800 Oe perpendicular field switched L 10 FePt particles with a mean size of 6 nm from in-plane arrangement in as-deposited state to out-of-plane orientation. A 5000 Oe in-plane field successfully defined nanoparticles with in-plane texture. These results demonstrated the feasibility of preparing nanoparticle-based magnetic recording media and exchange-spring-type permanent magnets with desired magnetic orientation control. Only involving thermal fluctuation as the obstacle, this approach makes an ideal subject for theoretical understanding and further optimization.
Bibliographical noteFunding Information:
This work was performed as part of the Information Storage Industry Consortium (INSIC) program in Heat Assisted Magnetic Recording (HAMR), with the support of the U.S. Department of Commerce, National Institute of Standards and Technology, Advanced Technology Program, Cooperative Agreement No. 70NANB1H3056. The authors thank Heraeus Corp. for partial financial support, C. Leighton for the usage of SQUID, and Yunhao Xu in our group for useful discussion.