Effect of RuAl and TiN Underlayers on Grain Morphology, Ordering, and Magnetic Properties of FePt-SiO Thin Films

The impact of RuAl underlayers and TiN intermediate layers on the microstructure, L1 ordering, and coercivity of granular FePt thin films is evaluated with an emphasis on controlling the FePt grains by using a new underlayer system. The use of the single RuAl/TiN film stacks does not help induce the epitaxial grain pick-up for FePt media due to their overly small grain size and smooth surface morphology. Two-step-deposited RuAl layers are developed to make a more open microstructure. By sputtering the top RuAl layers at low power and high Ar pressure, it is shown that there is a one-to-one grain matching between RuAl/TiN and FePt. It is also found that TiN underlayers are more favorable to the L1 ordering process compared to MgO underlayers. Index Terms—Grain morphology, L1 FePt, ordering, RuAl, TiN. I