Materials World Network PI visited National Tsing Hua Univ.(NTHU) in Taiwan three times

1. Fingerprinting Magnetic Nanostructures with Perpendicular AnisotropyKai Liu, University of California-Davis, DMR 1008791 Understanding how interactions within magnetic systems affect the reversal process is critical to the development of future magnetic recording media, sensors and other devices. Using the First Order Reversal Curve (FORC) method we have found an interesting magnetic memory effect where arrays of Ni nanowires “remember” the maximum reversal field they have been exposed to, due to strong dipolar interactions within the array. The corresponding FORC distribution is a vertical ridge pattern (Fig. 1). Similar patterns are also seen in perpendicular magnetic recording media (Fig. 2), where the competition between exchange and dipolar interactions is complex. Details of the distribution map out and uniquely identify inhomogeneities in these media, establishing a simple correlation with their media performance (in collaboration with Univ. of Delaware, Seagate, National Tsing Hua Univ., and NIST). X. M.Kou, et. al, Adv. Mater. 23, 1393 (2011); B. F. Valcu, et. al, IEEE Trans. Magn., in press. Fig. 1. FORC’s of an array of Ni nanowires (a) and the corresponding FORC distribution (b). The remanent magnetization uniquely corresponds to the reversal field. Fig. 2. FORC distribution from single-layer (left) and a multilayer (right) magnetic recording media. The tail of the “wishbone” structure is largely suppressed in the latter, corresponding to a better type of media.

2. Fingerprinting Magnetic Nanostructures with Perpendicular AnisotropyKai Liu, University of California-Davis, DMR 1008791 • Materials World Network • PI visited National TsingHua Univ.(NTHU) in Taiwan three times • U.C. Davis (UCD) graduate student Dustin Gilbert visited NTHU for 1 month in May 2011 • NTHU PI Prof. Chih-Huang Lai visited UCD for 1 month in July 2011 • Collaboration with NIST on neutron scattering, SEMPA, and HRTEM • Exchange graduate student, Ms. Alicia Gomez Gutierrez, from Universidad Complutense - Madrid, Spain, worked in PI’s lab during July-November 2010 • PI was part of a UCD delegation to visit Tokyo University of Science (TUS), Japan, for establishing a joint Master’s degree program in Chemical Engineering and Materials Science • As Program Co-Chair, PI co-organized the 2011 International Magnetics Conference (Intermag) in Taipei, Taiwan during April 25-29, 2011, sponsored by the IEEE Magnetics Society: 1,911 digest submissions, 1,538 accepted from 49 countries. (Left) UCD graduate student Dustin Gilbert (2nd left-most in last row) on NTHU campus, Taiwan, in May 2011. (Right) UCD-TUS agreement signing ceremony in Tokyo, Japan on Dec. 7, 2010. (Left) PI handing out a Best Poster award to a graduate student as the 2011 Intermag Conference Program Co-Chair. (Right) Intermag General Chair, Ching-Ray Chang, acknowledging the Program Co-chairs during the plenary session.