Papers by Keyword: FePt

Abstract: Superstructure transformation processes in intermetallics have beenstudied at the atomistic scale using Monte Carlo algorithms within two dis-tinct models: two-body interactions Ising-like system and Analytic Bond-Order Potentials. The transformation from “in-plane” to “off-plane” L10 vari-ant in [001]-oriented FePt nano-layers was observed and analysed by analyt-ical calculations providing clear explanation of the origin of the process, aswell as by “rigid-lattice” and “off-lattice” Monte Carlo simulations showingthe kinetics of the superstructure transformation.

Abstract: The main goal of this study is to investigate the structural and magnetic properties of FePt thin film with respect to the annealing tempreture. The FePt thin films were deposited by RF magnetron sputtering on Corning glass substrates at a room temperature. The films were then post-annealed at the Range of 575-675°C for 20 s by rapid thermal annealing (RTA) at a high heating ramp rate of 100 °Cs. Phase identification of thin films was performed using X-ray diffraction (XRD). With employing SEM, the size and uniformity of grains were studied. Moreover magnetic properties of annealed thin films were evaluated using a vibrating sample magnetometer (VSM). XRD results showed that the ordered FePt structure is formed at 625°C. According to the hysteresis loops, maximum out-of-plane and in-plane coercivity reached 7kOe. this value was achieve at 675°C .These results reveal its significant potential as magnetic recording media for high-density recording.

Abstract: C/FePt/Ti nano-thin films were prepared by DC facing-target magnetron sputtering system onto glass substrates at room temperature and subsequently in situ annealed for 500 °C 30 min in vacuum. The influence of C capping layer on microstructural and magnetic properties of the FePt films were investigated in detail. Atomic force microscopy (AFM) images indicate that C can effectively isolate the particles, refine particle, and distribute; however, the particle size distribution is uneven for too much C. The easy magnetic axial orientation is changed with the C layer thickness.

Abstract: The preparation of a novel ferrofluid out of one-dimensional magnetic structures is attempted by the reverse-micelle-based wet-chemical formation of FePt nanowires and nanorods. The latter were found to manifest lengths ranging from 25 to 250 nm, with an average diameter of only 1.5 to 2 nm. X-ray diffraction and high-resolution TEM revealed a polycrystalline microstructure, with individual grains having the disordered fcc structure in the as-prepared state; a thermally induced transition to the chemically ordered phase was observed around 550°C. The samples were determined to be superparamagnetic at room temperature, with the blocking temperature measured to be ~26 K.

Abstract: The L10 ordered MPt(001) thin films (M = Fe or Co) are very interesting for perpendicular recording due to their magnetic anisotropy and magneto-optical behaviours. Epitaxial L10-ordered NiPt(001) / FePt(001) bi-layers were co-deposited on MgO(100) substrates by MBE. The L10 order parameter is high with the concentration modulation along the growth direction. Some FeNiPt2(001) thin films were obtained by interdiffusion of the bilayers. The long-range-order parameter is conserved after interdiffusion (S = 0.75 ± 0.06), which can be explained by different mechanisms: a second-neighbour jump, a six-jump cycle, an anti-structural bridge mechanism or an antisite-pair elimination and creation mechanism, a double vacancy or a triple defect diffusion mechanism. Quenched molecular dynamics calculations in the frame of the second moment approximation of the tight binding method have been performed to obtain the energetic paths of the different mechanisms. The secondneighbour vacancy jump, the simultaneous jumps of bivacancies and the triple defect mechanisms can be ruled out for energetic reasons.