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Room-temperature x-ray diffraction and Mössbauer effect techniques have been used to characterize the structural features and local atomic environments of sputtered Fe[sub 51]Pt[sub 49] thin films following various isothermal treatments. Both techniques show that no significant changes occur in the chemically ordered L1[sub 0] tetragonal phase after it has formed. In contrast, changes in the disordered face-centered-cubic (fcc) phase are observed prior to the transformation into the ordered tetragonal phase. Mössbauer measurements indicate the development of increasing short-range order in the disordered fcc phase with increasing annealing temperature. Asymmetries in the fcc x-ray diffraction profiles also suggest the presence of lattice distortions caused by atomic size differences commonly found in the quenched disordered fcc phase of materials that form ordered structures. Quasi-real-time kinetic measurements of the disorder→order transformation in sputtered Fe[sub 51]Pt[sub 49] thin films within the temperature range 300 °C≤T≤400 °C have also been conducted using high-temperature x-ray diffraction techniques. Significant differences are observed between the kinetic parameters determined in this study and those of previous reports. It is proposed that these differences arise from the lower temperature range investigated in the present work, where the gradual changes occurring in the fcc phase can influence the rate of the ordering transformation. Furthermore, because the initial state of disorder in Fe[sub ∼50]Pt[sub ∼50] films can be influenced by the deposition conditions, variability in the low-temperature ordering kinetics should be expected among Fe[sub ∼50]Pt[sub ∼50] films prepared under different conditions. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The L10 ordering kinetics strongly depend on the films initial Fe/Pt atomic ratio. FexPt100-x films with x<50 at.% benefit from Cu addition since the Cu is expected to alloy with the FePt as an Fe atom replacement. The addition of Cu is less remarkable in films that start with an equiatomic Fe and Pt composition. In that case, Cu decreases the ultimate film coercivity and does not significantly improve the L10 ordering process. Large fields (9 T) are required to fully saturate the (1 1 1) textured L10 ordered FePt(Cu) films. It has been theoretically suggested that the moment of ordered FePt decreases due to ferrimagnetic alignment of the Fe and Pt moments; however, in these experiments the Ms value did not change significantly with annealing treatment and subsequent L10 ordering. [Copyright &y& Elsevier]

The influence of thin Pd and Pt buffers on the magnetic and structural properties of high moment Fe70Co30 thin films has been studied. A 50 nm thick FeCo film with no buffer showed isotropic magnetic characteristics and a coercivity of 40 Oe. Use of the Pd or Pt buffer reduced the coercivity of 50 nm FeCo films to about 15 Oe with more defined uniaxial properties. Reduction in the average FeCo grain size and clearly defined columnar grain boundaries were observed in these films. When the FeCo film thickness was increased to 200 nm, the FeCo no longer exhibited soft magnetic properties, regardless of the buffer material. A large increase in average column width was also observed in the 200 nm thick film. [Copyright &y& Elsevier]

The influence of oxide additives on the magnetic and structural properties of FePt L10 thin films has been studied. FePt films with HfO2 additive grown on a 5 nm MgO buffer showed a primarily random texture for both as-deposited and annealed samples. The average grain size was limited to 10 nm and the perpendicular coercivity was 1.3 kOe for a 10 nm thick FePt +20% HfO2 film annealed at 650°C for 10 min. In direct contrast, MnO additive neither limited grain size nor L10 ordering in annealed FePt films. A 10 nm thick FePt+20% MnO film grown on a 5 nm MgO buffer showed a unique discontinuous microstructure composed of clusters of (0 0 1) textured L10 grains after being annealed at 650°C for 10 min. The average size of the grains making up these clusters was 50 nm and the perpendicular coercivity of the film exceeded 7 kOe. [Copyright &y& Elsevier]