Magnetic Properties of L1_0 Fe-Ni-Pt Films for Heat Assisted Magnetic Recording(Selected papers from MORIS 2006 Workshop on Thermal & Optical Magnetic Materials and Devices)

概要

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Very high uniaxial anisotropy K_u as well as a moderate Curie temperature is required for magnetic materials by heat assisted magnetic recording (HAMR). Crystalline structure and magnetic properties of Fe-Ni-Pt thin films deposited on quarts glass substrates have been investigated in order to obtain optimum composition for the HAMR. L1_0 phase is found in Fe_<60>-xNi_xPt_<40> (x=0 to 24) with c-axis aligned in the perpendicular direction to the film plane. As Ni content x increases, the quality of (001) orientation is improved, while the order parameter S is gradually degraded. As a result, K_u in the perpendicular direction to the film plane is decreased from 3×10^7 erg/cm^3 for Fe_<60>Pt_<40> to 1×10^7 erg/cm^3 for Fe_<45>Ni_<15>Pt_<40> film. The Curie temperature measured is decreased with Ni content to 320℃ for Fe_<45>Ni_<15>Pt_<40>. Thermal simulation on the Fe-Ni-Pt disk assuming the similar film structure as current perpendicular recording media has revealed that the temperature rise above 350℃ is available by the laser irradiation with a power of 2mW and pulse width of 2ns. Therefore, Fe-Ni-Pt can be a candidate material with high anisotropy and optimum Curie temperature suitable for the HAMR.
2006-11-01