Prof. Katsuji Nakagawa, Associate Prof. Arata Tsukamoto, Prof. Akiyoshi Itoh (Now, Emeritus Professor ), and Associate Prof. Shinichiro Ohnuki received the Paper Award 2013 for ultra high density information recording from Magnetic Society of Japan.

Thermally assisted magnetic recording using a plasmonic effect was demonstrated experimentally by ultra-short time laser pulse heating and the plasmonic effect was simiulated. This paper is a collaborated results beween Nihon University and Tohoku University.

K. Nakagawa, A. Tajiri, K. Tamura, S. Toriumi, Y. Ashizawa, A. Tsukamoto, A. Itoh, Y. Sasaki, S. Saito, M. Takahashi, and S. Ohnuki, "Thermally Assisted Magnetic Recording Applying Optical Near Field with Ultra Short-Time Heating", J. Magn. Soc. Jpn. Vol.37 (2013), pp119-122.　doi:10.3379/msjmag.1302R016

To study thermally assisted magnetic recording focusing on surface plasmon effect as well as thermal diffusion effect, a 90-femto-second laser pulse impinged upon surface plasmon antennas on Co55Pt30Cr15?SiO2 granular film. It is important to use a femto-second laser pulse to analyze those effects, because the effects can be degraded by the thermal diffusion during the laser pulse duration if a longer laser pulse is applied. A SiN dielectric inter-layer was fabricated to keep an accurate distance between the antennas and the granular film. Written magnetic domains caused by surface plasmon effect were clearly observed by a magnetic force microscope. The minimum domain corresponded to 166 nm × 120 nm in size even though the laser spot diameter was about 50 μm. The surface plasmon effect was evaluated by the Finite-Difference Time-Domain method, and the thermal diffusion effect was also calculated to study thermally assisted magnetic recording.

This work is partly supported by Nihon University Strategic Projects for Academic Research.