Журнал наномедицины и нанотехнологий

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Magnetic Properties of Fe55Pd45 Films Deposited on Si (100) Nano-meter Wide Pillars

Chi-Ching Liu, Shien-Uang Jen, Jiann Shieh, Jenh-Yih Juang, Yuan-Ming Chang, Han-Hsiang Chian and Huang-Wei Chang

Magnetic nano-dot arrays with (tilted) perpendicular anisotropy are useful for the high-density magnetic recording. In this study, we deposited two kinds of ferromagnetic sample: Fe55Pd45/Si (100)-plane and Fe55Pd45/Si (100)-pillar. Each sample underwent a rapid thermal annealing (RTA) treatment; with a heating rate of 40oC/sec up to 500oC, being annealed there for 30 minutes, and then quenched to room temperature. After fabrication, X-ray diffraction (XRD) indicated that after RTA the FePd alloy transformed from the fcc to the fct phase with lattice constants: a = 0.380 nm and c = 0.378 nm. The Si(100) pillars are 500 nm in length, 65nm in diameter, and with a density of about 1012 cm-2. On top of each Si(100) pillar there sat a prolate ellipsoid shape Fe55Pd45 particle: length L ≅ 108 nm and short-axis diameter
d ≅ 67 to 83 nm. Magnetic domain (MD) pattern of the FePd nano-dot array was studied by magnetic force microscopy (MFM). The overall magnetic domain size (D) is from 285 to 452 nm. The squareness ratio (SQR) of the magnetic hysteresis loop reaches as: (SQR)z = 0.65 > (SQR)y = 0.45 >(SQR)x = 0.40 for the FePd/Si(100)-pillar film. From the inplane rotation angle (φ) and the out-of-plane tilting angle (θ) dependencies of the coercivity (HC), we find that the former exhibits the characteristics of the curling-mode-like switch, while the latter exhibits the Stoner-Wohlfarth-like switch.