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The characteristics of exchange-biased soft underlayers (SULs) were investigated using magnetic force microscopy and spin stand measurements with a single-pole (focused ion-beam trimmed gap) writer and magnetoresistive head. The SUL high-moment materials (FeCoB, FeAlN) were exchange biased by using IrMn. Spin stand data on perpendicular media (CoCrPtB) with an exchange-biased FeCoB SUL also showed a low integrated dc erase noise level, demonstrating its potential for use in double-layered perpendicular media. Index Terms--Exchange biasing, media noise, perpendicular media, soft underlayers.

A new study investigates the structural and magnetic properties of sputtered Co50Fe50(CoFe) thin films.

Research was conducted to investigate the structural features of thin film ferromagnetic tunnel junctions. The magnetic layers were characterized by Co, Fe, and oxide barriers. The tunnel junctions were prepared by rf and dc reactive magnetron sputtering onto thermally oxidized silicon wafers. Results indicated that the oxide barriers of CoO and MgO were polycrystalline with many crystallites extending across the entire barrier thickness.

We discuss a method for the determination of activation volumes of reversal in perpendicular media. This method does not require correction for the self-demagnetizing field normally associated with these media. This is achieved by performing time dependence measurements at a constant level of magnetization. From the difference in time taken for the magnetization to decay to a fixed value at two fields separated by a small increment [DELTA]H, the activation volume can be determined. We report data for both CoCrPt alloy films and a multilayer film, typical of those materials under consideration for use as perpendicular media. We find activation volumes that are consistent with the hysteresis curves of the materials. The activation volume scales qualitatively with the exchange coupling. The alloy films have significantly lower activation volumes, implying that they would be capable of supporting a higher data density. Index Terms--Activation volume, fluctuation field, magnetic characterization, perpendicular recording media.

The use of stress anisotropy to increase the nucleation field of CoCrPt perpendicular media grown on a Ta/Hf buffer layer is presented. The annealing in air of a Ta/Hf/CoCrPt thin film structure resulted in a substantial increase in H(sub n).

The inclusion of a An layer in the magnetic tunnel junction structure Fe/MgO/CoFe substantially alters the magnetic properties. In this work we use zero field 59Co NMR to see if these changes in magnetic properties are correlated with changes in the local atomic environment. The technique of spin-echo NMR allows the effective magnetic field (hyperfine field) at the nucleus to be determined and so provides information on the local atomic environments including strain effects and magnetic moments. The results show that the local atomic environment of Co does not change significantly, however the r.f. power required to obtain the maximum signal is substantially different when the Au layer is included showing that the r.f. electronic enhancement factor changes appreciably. Index Terms - Magnetic tunnel junctions, NMR, Thin films.

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 structural features and local atomic environments of sputtered Fe51Pt49 films following various isothermal treatments are characterized using room-temperature x-ray diffraction (XRD) and Mossbauer effect techniques. The results of XRD and Mossbauer measurements show that no significant changes occur in the ordered L1(Sub 0) tetragonal phase of polycrystalline 500 Angstrom Fe51Pt49 films after the ordered phase is formed during thermal treatments at T(Sub ann) greater than or equal to 300 degrees C.

The temperature dependence of stress in thin films of Fe(sub x)Pt(sub 1-x) and Fe0.35Cu0.15Pt0.5 is discussed using the wafer curvature technique. This indicates that the transition to a low stress state is related to changes in the fcc structure prior to L1(sub 0) phase transformation.

A study was conducted to examine the influence of Cu, Ag, and Au additives on the L1(sub 0) ordering, texture, and grain size of FePt thin films. The result shows that the Ag and the Au additives affect the structural and magnetic properties of FePt in a similar manner.

Studies the tunneling properties of sputtered oxide barriers in lead (Pb)/oxide/ferromagnet junctions. Making the initial oxide/ferromagnet bilayer without breaking vacuum; Exposition of the bilayer to the atmosphere before the deposition of a Pb counterelectrode in a separate vacuum chamber.