Perpendicular Magnetic Anisotropy Analysis for L10-Typed FePt Granular Media With Various Grain Boundary Materials by 90 kOe Torquemetry

Takashi Saito,Kim Kong Tham,Shin Saito,Tomoyuki Ogawa,Ryosuke Kushibiki

doi:10.1109/tmag.2020.3015515

Abstract

Perpendicular 90 kOe torquemetry analysis of magnetic anisotropy (K u⊥ exp ) for L1 0 -typed FePt granular media with various grain boundary materials (GBMs) was conducted. According to the analysis for granular films with a constant GBM volume of 30 vol% deposited at a high substrate temperature, K u⊥ exp was not dependent on the saturated torque coefficient of fourfold components (L 4θ sat ) but was dependent on that of twofold components (L 2θ sat ) originating from magnetic grains with c-axes normal to the film plane. Furthermore, L 4θ sat mainly originated from FePt grains with c-axes parallel to the film plane. K u⊥ exp also had a strong correlation with grain diameter (GD) and degree of order (Sin). On the other hand, K u⊥ exp had no significant correlation with the melting point (Tm) of the GBM, which indicates that the dominant factor affecting K u⊥ exp was not phase separation. Based on these evaluations, an increase of GD caused an increase of Sin, regardless of the GBMs, which resulted in enhancement of K u⊥ exp for the FePt granular films.

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