A high throughput study of both compositionally graded and homogeneous Fe–Pt thin films (original) (raw)
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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.
Effect of Pt layers on chemical ordering in FePt thin films
The tunability in the structural and magnetic phases present in RFsputtered Fe 3 Pt thin films over Si (1 0 0) substrates have been studied by introducing thin films of platinum (Pt) as an underlayer and/ or overlayers. Annealing of the Fe 3 Pt thin films with Pt underlayers (Pt/Fe 3 Pt) structures at 600°C for 1 h, indicates well organized nanostructured grains as imaged through an atomic force microscope (AFM). The evolution of superstructure peaks as well as the preferred orientation along (0 0 1) plane observed in the X-ray diffraction (XRD) study is well supported by the magnetic measurements. These annealed Pt/Fe 3 Pt structures show high magnetocrystalline anisotropy and the presence of hard phase with a coercivity of 8.5 kOe. Here, the annealing process allows the adjacent Pt atoms to diffuse into the Fe 3 Pt unit cells and triggers the structural transformation to chemically ordered L1 0 phase. An additional L1 2 phase is observed in the annealed Fe 3 Pt thin films with Pt overlayer and underlayer (Pt/Fe 3 Pt/Pt) tri-layered structures.
FePt films prepared by DC sputtering on Si h100i substrates when annealed at 600 C for 1 h exhibited a structurally ordered and magnetically hard L10 phase. These FePt films were exposed to dense electronic excitations by using 100MeV oxygen ions as a function of increasing fluences. Such excitations induce pressure and result in the enhancement of order parameter by increasing strain on the FePt films. Apart from this, the surface morphological images from field emission scanning electron microscopy reveal a densification of the films consequent to irradiation and are correlated with the details obtained from Rutherford back scattering analysis. The variation in the values of coercivity correlates well with the change in volume percentage of face centered tetragonal and face centered cubic phase. A coercivity of 14.7 kOe with order parameter 0.92 is achieved at a fluence of 51012 ions/cm2. The theoretical simulation of the demagnetization curve shows a strong correlation of coercivity and order parameter between the experimentally obtained values with that of simulation. The effect of irradiation induced strain, the structural ordering and coercivity of FePt films as a function of fluences have been discussed.
Largely enhanced coercivity of FePt film at low temperature by introduction of CrRu underlayer
Journal of Magnetism and Magnetic Materials, 2007
In situ ordered L1 0 FePt films with large coercivity have been prepared at low temperature by DC magnetron sputtering the FePt magnetic layer on a CrRu underlayer with preheated natural-oxidized Si (1 0 0) wafer substrates. The results showed that granular L1 0 FePt nanoparticles with a large in-plane coercivity of 4000 Oe and an isolated uniform size of 10.7 nm can be achieved by introducing a 50 nm CrRu underlayer under the 25 nm FePt film deposited at a low substrate temperature of 350 1C. r
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
The effect of Bi additives on the properties of Fe-Pt films
Journal of Physics and Electronics
Using the modernized three-electrode ion-plasma sputtering method, homogeneous thin films of FePt and Fe (Pt/Bi) were obtained. Films were deposited on NaCl and glass-ceramic substrates. The film thickness was 120-530 nm. In this case, the calculated cooling rate reached ~ 1012–1014 K/s. The structure of the FePt and Fe (Pt/Bi) films was investigated using X-ray diffraction and electron microscopy methods. It was established that metastable phases were formed in freshly sputtered films, including a supersaturated solid solution, a nanocrystalline and amorphous phases. It was determined that the obtained metastable structures are stable when heated to 540-880 K, depending on the composition. It was established that Bi additives significantly reduce the coercive force of films in the as-sputtered state. It was shown that a heat treatment increased the coercive force up to 36 kA/m in FePt films and up to 10 kA/m in Fe (Pt/Bi) films. The composition of Fe (Pt/Bi) films with a small valu...
High coercivity FePt thin films with Ag intermediate Layers deposited at 400/spl deg/C
IEEE Transactions on Magnetics, 2000
1 0 phase FePt thin films deposited on amorphous Corning glasses and single crystal MgO (100) substrates were investigated. Epitaxial growth of the FePt (001) films was observed on MgO substrate at a deposition temperature of 400 C. With ultrathin Ag intermediate layers deposited between FePt layers, the film structure changed from interconnection network to isolated-island character. The perpendicular coercivity of the FePt film increased to about 32 kOe with intermediate layers inserted. The improvement of the magnetic properties may be attributed to the formation of island structures by the additive Ag layers in the FePt films. Index Terms-Ag, epitaxial growth, FePt, high coercivity, intermediate layer, MgO, perpendicular magnetic recording.
Magnetic properties and microstructure of low ordering temperature L1[sub 0] FePt thin films
Journal of Applied Physics, 2004
Polycrystalline Fe 52 Pt 48 alloy thin films were prepared by dc magnetron sputtering on preheated natural-oxidized silicon wafer substrates. The film thickness was varied from 10 to 100 nm. The as-deposited film was encapsulated in a quartz tube and post-annealed in vacuum at various temperatures for 1 hour, then furnace cooling. It is found that the ordering temperature from as-deposited soft magnetic fcc FePt phase to hard magnetic fct L1 0 FePt phase could be reduced to about 350 o C by preheating substrate and furnace cooling treatment. The magnetic properties measurements indicated that the in-plane coercivity of the films was increased rapidly as annealing temperature is increased from 300 o C to 400 o C, but it decreased when the annealing temperature is higher than 400 o C. X-ray diffraction analysis shown that the as-deposited FePt thin film was disorder fcc FePt phase. The magnetic measurement indicated that the transformation of disorder fcc FePt to fct L1 0 FePt phase was started at about 350 o C which is consistent with the analysis of X-ray diffraction patterns. From scanning electron microscopy (SEM) observation and selected area energy disperse spectrum (EDS) analysis, the distributions of Fe and Pt elements in the films were become non-uniform when the annealing temperature was higher than 500 o C 2 due to the formation of Fe 3 Pt phase. After annealing at 400 o C, the in plane coercivity of Fe 52 Pt 48 thin film with film thickness of 100 nm is 10 kOe, Ms is 580 emu/cm 3 , and grain size is about 12 nm.