We propose a bit patterned media fabrication method based on low energy nitrogen ion implantation. Nitrogen ion implantation of fcc-Co/Pd multilayer or hcp-CoCrPt single layer suppresses their magnetizations at room temperature. Ion implantation reduces the Curie temperature from 600 to 400 K (or lower) as a result of lattice expansion and reduced exchange interaction between the magnetic atoms in the magnetic layer. We have made media with magnetic dots of 190 to 30 nm in diameter by nitrogen ion doping through resist patterns. Writing and reading of the signal from individual dots were performed with a commercial perpendicular magnetic recording head.

In this paper, we report on an interface dipole modulation (IDM) loss occurring in HfO2/atomically thin TiO2/SiO2 stack structures prepared by atomic layer deposition (ALD). The IDM characteristic, which is observed as a capacitance–voltage (C–V) hysteresis curve, disappears when the temperature during ALD or post-deposition annealing exceeds its respective critical temperatures, even though the HfO2/SiO2 stack structure is maintained. We found a correlation between Ti suboxide formation and IDM loss and speculated the effect of impurities and defects introduced during the ALD process on IDM operation.

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