Temperature Dependence and Microstructure Effects on Magnetic Properties of FePt(B, Ag, C) Film

Abstract

A FePt(B, Ag, C) granular film was formed from post-annealed B4C(1.0 nm)/FePt(Ag, C) layers at a substrate temperature of 470 °C for 2 min. The 6 nm thick FePt(B, Ag, C) film demonstrates high perpendicular magnetic anisotropy (Ku = 2.83 × 107 erg/cm3 at 100 K) and out-of-plane coercivity (Hc = 38.0 kOe at 100 K). The Ku and out-of-plane Hc are respectively increased from 38% and 46% between 350 K and 50 K. The sample with a thickness of 8 nm also shows a similar trend for magnetic properties; however, the tiny magnetization kink which may come from rare Fe-B or disordered FePt grains was observed in the easy axis loop. The intrinsic (ΔHint = 12.6 kOe) and extrinsic switching field distribution (ΔHext = 1.62 kOe) were characterized by major and minor loops to correlate the microstructural grains. The coupled FePt grains grown on a single MgTiON grain were observed in a high-resolution transmission electron microstructure (HRTEM) image. This small intergranular exchange coupling was defined by estimating the magnetic cluster size (46.6 nm) from ΔHext and the average grains size (28.2 nm) from TEM images. The temperature dependence of coercivity was fitted to further understand the magnetization reversal process. The lower microstructural parameter was evidenced in the imperfect grain morphology.

Magnetic Properties and Microstructure of FePt(BN, X, C) (X = Ag, Re) Films

“…From the spectra line shape shown in Figure 5 and Figure 6 a, there are distinctive shoulders at the binding energy around 710 eV and 720 eV, and the Fe 2p3/2 and 2p1/2 core-level binding energy was considered and the Fe 3 O 4 phase was observed both in FePt(BN, Ag, C) and FePt(BN, Re, C) films. The magnetite Fe 3 O 4 (ferrimagnet) is a soft magnetic material and responds to the slight kink illustrated in the out-of-plane magnetization curves at zero field in Figure 2 a [ 33 , 34 ].…”

Switching Field Distribution in BN/FePtCAg/MgTiON and FePtCAg/MgTiOBN Films

“…When the field of recoil loop increased up to the coercivity field, 50% of the FePt grains on the easy axis switched and the magnetostatic interaction between grains was not considered. The grain size variation (σ volume ), the magnetocrystalline anisotropy deviation (σ Hk ), and the c-axis(σ axis ) misalignment belong to intrinsic SFD and grains coupling (dipolar- or exchange-interaction) is extrinsic SFD [ 4 , 17 , 27 , 28 , 29 ]. The dimension, structure- and magnetic- alignment of each grain was discussed in ΔH int and the interaction between many grains was considered in ΔH ext .…”