Orbital magnetic moment and coercivity of SiO2-coated FePt nanoparticles studied by x-ray magnetic circular dichroism

Article

关键词: SIO2-NANOREACTOR METHOD;    MONODISPERSE;   

DOI  :  10.1103/PhysRevB.90.024423

来源: SCIE

【 摘 要 】

We have investigated the spin and orbital magnetic moments of Fe in FePt nanoparticles in the L1(0)-ordered phase coated with SiO2 by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe L-2,L-3 absorption edges. Using XMCD sum rules, we evaluated the ratio of the orbital magnetic moment (M-orb) to the effective spin magnetic moment (M-spin(eff)) of Fe to be M-orb/M-spin(eff) = 0.08. This M-orb/M-spin(eff) spin value is comparable to the value (0.09) obtained for FePt nanoparticles prepared by gas phase condensation, and is larger than the values (similar to 0.05) obtained for FePt thin films, indicating a high degree of L1(0) order. The hysteretic behavior of the FePt component of the magnetization was measured by XMCD. The magnetic coercivity (H-c) was found to be as large as 1.8 T at room temperature, similar to 3 times larger than the thin film value and similar to 50 times larger than that of the gas phase condensed nanoparticles. The hysteresis curve is well explained by the Stoner-Wohlfarth model for noninteracting single-domain nanoparticles with the H-c distributed from 1 to 5 T.

【 授权许可】

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