Templated Growth of L10-FePt for HAMR Media

Abstract

Granular L10-FePt thin film deposited on (002) textured MgO underlayers have come long way in the support of the present HAMR media areal density capability. However, further reduction of the center-to-center pitch distance between adjacent grains below 6nm is meeting the nucleation density limit of this media/underlayer material combination [1]. Here, we present a novel fabrication method utilizing metal-oxide/nitride materials systems with two-phase separation to develop a pre-defined and robust oxide/nitride template to increase the nucleation density and the columnar growth of L10-ordered FePt grains. The template is directly formed on top of MgO underlayer by co-sputtering metal and oxide/nitride materials, resulting in metal particles embedded in the oxide/nitride matrix. This is followed by the selective etching of the metal nanoparticles from the matrix [2]. Experimental demonstration shows that FePt can be backfilled into the “craters” left by the metal nanoparticles with the correct texture on the MgO underlayer. By comparing the mean pitch distance of FePt grains without and with template layer in Fig. 1, it is shown that the nucleation density of FePt grains is determined by the areal density of the “craters” formed in Au-SiO2 template layer. With the help of such a fabrication method, the material choices for further reducing the pitch distance of the FePt grains in HAMR media are expanded. The several combinations of various matrix materials forming the template and their results on nucleation and growth of FePt will be presented and discussed.