The effect of Bi additives on the properties of Fe-Pt films (original) (raw)
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A high throughput study of both compositionally graded and homogeneous Fe–Pt thin films
Journal of Materials Research and Technology, 2022
Compositionally graded Fe-Pt thin films were prepared on stationary 100 mm Si substrates by magnetron sputtering a base target of Fe on which a piece of Pt is asymmetrically positioned. Energy Dispersive X-Ray analysis was used to map the variation in film composition across the substrate, as a function of the size of the Pt piece. A scanning polar Magneto-Optical-Kerr-Effect system was used to probe the influence of composition and post-deposition annealing conditions (temperature and time) on coercivity. In this way the maximum coercivity achievable for the sputtering system used could be established in a high throughput fashion. The evolution in coercivity with composition was correlated with the formation of L10 FePt and changes in its lattice parameters, as determined by scanning X-ray diffraction. High throughput coercivity mapping was then carried out on homogeneous Fe-Pt thin films of different composition treated to different annealing conditions. This study serves as a step towards the integration of coercive FePt films into collectively fabricated devices.
On the influence of composition on laser-deposited Fe–Pt films
Journal of Magnetism and Magnetic Materials, 2005
Pulsed laser deposition from elemental targets was used to prepare L10 ordered Fe–Pt films directly on heated MgO(100) substrates. The influence of composition on the c-axis lattice parameter, microstructure and coercivity is examined. Strong (001) texture and maximum coercivities above 5T were observed for slightly Pt-rich compositions. When Fe droplets are produced during the ablation process, an additional phase without
Russian Journal of Non-Ferrous Metals, 2020
The main trends in the modern development of magnetic microelectronics are miniaturization and operation speed, while ensuring efficient operation in the MHz and GHz frequency ranges of magnetic fields. Creating new magnetic materials characterized by properties providing these trends is the most important fundamental and applied problem of materials science. In this regard, nanocrystalline soft magnetic alloys belonging to Fe-Me-X systems (Me is one of the metals of the IVb group of the periodic table; X is one of the light elements N, C, O, or B) obtained in the form of films attract great attention. Such films produced by magnetron sputtering and characterized by the Fe/MeX two-phase structure are capable, as was shown earlier by the authors of the present article using the example of Fe-Zr-N films, of providing a combination of high saturation induction B s , low coercive field H c , and high hardness and thermal stability of the structure. The films were prepared by magnetron sputtering. In accordance with the initial data obtained by the authors, the films of the FeTiB system can provide better properties as compared with FeZrN films. The published data on FeTiB films in the context of their application in microelectronic devices are very sparse. In the present work we continue studies of FeTiB films aimed at identifying the chemical and phase composition providing the level of properties required for the application of the films in microelectronics. The nanocrystalline films containing from 0 to 14.3 at % Ti and from 0 to 28.9 at % B are obtained by DC magnetron sputtering. The phase-structural state of the films is studied by X-ray diffraction and transmission electron microscopy. According to the phase composition, all films are divided into three groups: single-phase (supersaturated solid solution of Ti in α-Fe), two-phase (α-Fe(Ti)/αTi, α-Fe(Ti)/TiB 2 , α-Fe(Ti)/FeTi, and α-Fe(Ti)/Fe 2 B), and XRD amorphous. The XRD amorphous films are shown to be characterized by a mixed structure made of a solid solution α-Fe(Ti) with a grain size in the range from 0.7 to 2 nm and an amorphous phase. A reasonable assumption has been made that the amorphous phase is enriched by boron. A quantitative assessment of the grain size of the α-Fe(Ti) phase and its dependence on the chemical and phase composition of the films is given. The mechanisms of solid-solution and dispersion strengthening determine the grain size of this phase.
MRS Proceedings, 1996
In this study, defect-free Pt films with good adhesion were deposited on SiO2/Si substrates by a two-step magnetron sputtering. This method consists of the first sputtering step using Ar/O2 gas mixture and the second step using Ar. After two-step deposition, an annealing process was followed at 600-1,000 °C in ambient atmosphere. In the first step, oxygen containing Pt films were deposited. Oxygen incorporated in the Pt films completely diffused out during the high temperature annealing. After the annealing process, the film became dense without catastrophic failures such as hillock, pinhole or buckling. Adhesion strength of films produced by this process was good enough to pass a tape test. It is believed that the good adhesion and the observed microstructural evolution are related to the oxygen in Pt films introduced during the first sputtering step. Adhesion, microstructural evolution and the role of oxygen in Pt films are briefly discussed.
Journal of Physics: Conference Series, 2008
Ultra thin platinum films were grown by dc magnetron sputtering on thermally oxidized Si (100) substrates. The electrical resistance of the films was monitored in-situ during growth. The coalescence thickness was determined for various growth temperatures and found to increase from 1.3 nm for films grown at room temperature to 1.8 nm for films grown at 250 • C, while a continuous film was formed at a thickness of 3.9 nm at room temperature and 3.5 nm at 250 • C. The electrical resistivity increases with increased growth temperature, as well as the morphological grain size, and the surface roughness, measured with a scanning tunneling microscope (STM).
Competing magnetoresistance contributions in sputtered FePt thin films
Journal of Magnetism and Magnetic Materials, 2010
Fe-Pt thin films were deposited by rf sputtering on an MgO substrate heated at different temperatures to induce the formation of the perpendicular Fe-Pt L1 0 phase with a different grain morphology on the nanometer scale. All films are characterized by a mazelike pattern of FePt nanograins with interconnected bases. MFM images and magnetization curves indicate that all samples have a strong perpendicular magnetic anisotropy arising from (0 0 1) growth. The temperature behaviour of the electrical resistance indicates that a percolating path exists for conduction electrons in the mazelike pattern. The magnetoresistance was measured as a function of magnetic field (applied longitudinally) and temperature in the ranges À 70 kOe oH o + 70 kOe and 4 Ko T o150 K, respectively. All samples display a complex behaviour of the electrical resistance as a function of applied field. The role of the different magnetoresistance effects (both intrinsic and extrinsic) measured in these FePt thin films is elucidated.
In situ transmission electron microscopy of ion irradiated Fe–Pt alloy thin films
Journal of Applied Physics, 2006
We report the microstructural evolution during irradiation of FePt and FePt 25 at. % thin films sputter deposited onto electron transparent silicon monoxide substrates. The films were studied in situ for 500 keV Kr + irradiation up to a fluence of 10 15 ions/ cm 2 or 4 displacements/ atom ͑dpa͒. Upon irradiation to approximately 1 dpa, the initial disconnected granular morphology became continuous. In particular, for FePt, accelerated grain growth was observed once the continuous morphology was achieved during ambient temperature irradiation. No atomistic ͑chemical͒ ordering from the as-deposited A1 phase into either the L1 0 FePt or L1 2 Fe 3 Pt phases was observed during ambient temperature irradiation. After irradiation, the specimens were then in situ annealed. The intermetallic ordering temperature, compared to that of an unirradiated film, was lowered by Ϸ200°C for FePt 25 at. %. No decrease in the ordering temperature was observed for irradiated FePt. The rate of FePt grain growth during annealing was very similar for both irradiated and unirradiated films over the 25-650°C temperature range investigated.
Research on Chemical Intermediates, 2008
Studies of piezoelectric and electrostrictive properties of (1 − x)PMN-xPT thin films were carried out. We have chosen the compositions 90/10 and 70/30, which exhibit, respectively, mostly electrostrictive and piezoelectric behaviour in bulk material. Annealing temperature effects on PMN-PT structural, dielectric, ferroelectric and electromechanical properties have been investigated. We demonstrate that with conventional annealing the pure perovskite phase can be obtained at very low temperature (400 • C) without any pyrochlore phase for the two compositions. We show that electromechanical response is a mix between electrostrictive and piezoelectric response for the two compositions. However, as can be easily understood, piezoelectric contribution is larger for 70/30. It is shown that electrical responses of the films obtained at 400 • C are largely satisfied for many applications; for higher annealing temperature we observe an enhance of the electrical properties due to an improvement of the material quality in terms of crystalline structure.
Preparation of Fe/Pt Films with Perpendicular Magnetic Anisotropy
Hyperfine Interactions, 2005
We have investigated the microstructures and magnetic properties of L1 0 ordered equiatomic FePt thin films prepared by ion beam sputtering and subsequent annealing. It is observed from X-ray reflectivity and X-ray diffraction measurements that the mixing at Fe/Pt interfaces starts to occur with annealing and leading to the FePt alloy phase formation. The rapid increase in the coercivity values above 275-C, obtained from vibrating sample magnetometer (VSM) measurements, confirms the formation of the ordered L1 0 FCT FePt phase.