The magnetic and recording characteristics of Co-based thin film media are strongly influenced by microstructure. The media microstructural characteristics, in turn, depend on sputtering conditions of underlayers and magnetic layers. The role of Cr underlayer thickness and sputtering pressure have been reported previously. The present work examines the growth morphology and recording properties of a CoPtCr alloy on Cr underlayers where the deposition conditions such as sputtering pressure and rf bias were independently varied for the Cr underlayer and the magnetic layer. We find that the growth morphology of the magnetic layer is governed primarily by the deposition condition of the Cr underlayer. In particular, increased sputtering pressure for the Cr underlayer produces columnar morphology which induces isolation of the grains in the magnetic layer. This results in a significant reduction in the recording noise due to reduced intergrain exchange coupling. On the other hand, the application of ff bias during the deposition of the magnetic layer promotes more continuous magnetic grains, thereby increasing the recording noise. The observed trends in microstructure and recording noise can be understood qualitatively in terms of Thornton's microstructure diagram and the competition between micromorphological roughness and adatom mobility during the film growth.

The effect of thin Cr underlayers on the coercivity, the initial susceptibility, and micromagnetic structure of RF sputtered Co/Cr thin films have been studied. A reciprocal relationship between the initial susceptibility and the coercivity of the RF sputtered Co/Cr films were observed. Micromagnetic images of these Co/Cr films obtained by Fresnel mode Lorentz TEM revealed a refinement of the micromagnetic images correlated with a simultaneous increase in coercivity and decrease in initial susceptibility. Such behavior is expected in cases where the initial magnetization and magnetization reversal are hindered by the variation of local energy with the magnetic moment distribution. The interaction of the Cr underlayers with the Co magnetic overlayer very likely induces fluctuations in local magnetic energy of the Co films. Accordingly, the initial magnetization and magnetization reversal are likely to be impeded by fluctuations of the magnetic energy resulting in the observed increase in coercivity and decrease in initial susceptibility.

Co85Cr15-xTax(x:0, 2at%)/Cr films with microscopically flat surface were investigated for high density recording media. These films were deposited on silicon wafer and glass substrates at the substrate temperature Ts of 350 °C at argon pressure as low as sub-mTorr by using Facing Targets Sputtering (FTS) apparatus. The elevating of Ts promoted the Cr(200) orientation in film plane, leading to the in-plane c-axis orientation of Co crystallites. Addition of some elements such as Si, Ge and Ta in Cr thin film was found to stabilize Cr(110) crystal orientation even at Ts of 300 °C.

For media used in longitudinal recording, an epitaxial relationship is observed between the Cr and Co-alloy layers, and generally a strong Cr <100> texture is desirable for c-axis in-plane orientation of the Co alloy. In this study, Cr underlayer thickness, temperature and Cr deposition pressure were varied while keeping the magnetic layer (CoPtCr) deposition process constant. Films were deposited on circumferentially textured NiP, polished NiP and chemically elched NiP substrates as well as Si wafers in order to study the effects of surface finish on the crystallographic orientation of the Cr underlayer. The uniformity of the magnetic properties and in-plane anisotropy (orientation ratio) of the disks were measured using Kerr magnetrometry. The in-plane anisotropy was found to be related to the Cr deposition conditions and the surface texture of the NiP. Signal to noise ratio results and a possible mechanism for the origin of the in-plane anisotropy are discussed.

Co-Pt-B-O alloy films show the magnetic properties of saturation magnetic induction 4TπMs = 12 kG, perpendicular coercivity Hc(⊥) = 5 kOe, and perpendicular anisotropy field Hk(⊥) = 23 kOe. These characteristics are easily controlled by changing the film composition. The perpendicular magnetic anisotropy field and the coercivity of the Co-Pt-B-O alloy films have close correlation with the film microstructure. To clarify this relation, the individual effects of oxygen and boron in the Co-Pt binary alloy film were investigated. The addition of boron makes the average grain size smaller, whereas the column diameter remains unchanged. The addition of oxygen to the Co-Pt binary alloy reduces the column diameter to about 5–10 nm, whereas the columns are densely packed without any gaps. The sole addition of oxygen or boron neither increases the perpendicular anisotropy nor the coercivity. The high perpendicular anisotropy and the large coercivity are derived from the fine columnar structure of 5–10 nm in diameter coupled with the inter-columnar gaps of about 1 nm and are obtained by the co-additions of oxygen and boron.

The compositional distribution of Co-Cr vacuum evaporated films is investigated using the 59Co nuclear magnetic resonance technique. The dependence of the spin-echo spectra of Co-Cr films and powders on Cr concentration is measured. The spectra of the films evaporated at 260°C are found to be similar to those of powder samples with the Cr concentration of approximately 6 at%, although the Cr concentration of the films is between 10 at% and 24 at%. It is concluded that the Cr concentration of the ferromagnetic regions in Co-Cr films remains at 6 at%, although Cr concentration increased to 25 at%. The spin-echo spectra of the films evaporated at 160°C show that the Cr concentration in ferromagnetic regions is slightly higher than that found in the films deposited at 265 °C. This implies that segregation is less developed in the 160°C films The relationship between the magnetic properties and the segregation is also discussed

The atom probe field ion microscope has been used to characterize the morphology and determine the compositions of the iron-rich a and chromium-enriched α′ phases produced during isothermal and step cooled heat treatments in a Chromindur II ductile permanent magnet alloy. The good magnetic properties of this material are due to a combination of the composition of the two phases and the isolated nature and size of the ferromagnetic a phase. The morphology of the a phase is produced as a result of the shape of the miscibility gap and the step-cooled heat treatment and is distinctly different from that formed during isothermal heat treatments.

The microstructure of the electroless-plated CoNiReP/NiMoP doublelayered media was examined with various methods and the origin of the inplane anisotropy initial regions of the CoNiReP recording layers was discussed. It was confirmed that the initial region consists of randomly oriented fcc phase with Ni-rich composition, showing the granular condition, while the perpendicular anisotropy region at the top consists of <002> perpendicularly oriented hcp phase, showing the columnar structure. It is considered that the formation of the initial region is due to a preferential deposition of Ni onto the underlayers, and that the thickness of the initial region changes due to a change in the condition of the underlayers, especially that of deposition activity and/or morphology at their surfaces.

This paper reviews on magneto-optical spectroscopy of alloys, metallic multilayers and interference enhancement structures for magneto-optic (MO) recording. Mainly rare earth transition metal (RE-TM) alloys and Co/transition metal (Co/X) multilayers will be discussed. The read out performance in MO write/read tests is given by tile reflectivity and Kerr rotation strongly depends on the wavelength. While the magneto-optical transitions in the near infrared (IR:≈820nm) are dominated by tile 3d magnetic transition metals Fe and Co, the properties in the ultraviolet (UV: <400nm) can be dominated by either rare earths like Nd or Pr in RE-TM alloys or by exchange polarized Pt or Pd in Co/X multilayers and their respective alloys.

In an attempt to correlate the magneto-optic Kerr effect to electronic properties we have systematically investigated alloys and multilayers with x-ray photoemission (XPS) and polar magneto-optical Kerr spectroscopy (0.5–5.3eV range). It is found that electronic 4f levels in Nd or Pr contribute to the Kerr elffct via Γ→, d transitions in the order of 0.3°. Exchange polarized Pd and Pt in Co/X multilayers give rise to a room temperature Kerr rotation in the same order of magnitude via excitations of the 4d and 5d bands, respectively. These effects clearly depend on film compositions and thickness ratios.,

A systematic study on magnetic properties of (Fc/Pt) compositionally-modulated films as a function of substrate-deposition-temperature has been carried out. For films with (2.5ÅFe/18ÅPt)×40, the intrinsic perpendicular magnetic anisotropy Ku is found to increase with decreasing temperature for all the sarmples deposited at temperatures from -114 °C to 220°C during deposition. The higher the substrate-deposition-temperature, the larger the Ku values become. This result implies a possible contribution from the magne to-elastic effect to the total anisotropy. However, a major part responsible for the perpendicular anisotropy may be found in other mechanisms. The saturation magnetization is found to exceed the value for pure Fe at temperatures lower than 180K.

We have prepared Co/Pt multilayers by evaporation in UHV on MgO (100) substrates kept at various temperatures. Most of the samples were grown on a Pt buffer layer. Magnetic and magneto-optical properties have been studied. The surface anisotropy Ks for MgO substrates is 0.35 erg.cm−2 which is smaller than 0.6 erg.cm−2 obtained for glass substrates. The effect of the growth conditions on Ks is observed only for t(Co)<10 Å where the crossover to Keff>O occurs. Deposition at higher temperature leads to an increase in the coercivity. The magnetization and the anisotropy is practically temperature independent in the range 5 to 295 K. However the coercivity increases sharply below 100K.

Ultrathin epitaxial films grown in UHV – Fe(110) on Au(111) and Ag(111), Co(0001) on Au(111) – , sputtered Fe films between Ag and sputtered Fe/Au multilayers were studied by SQUID magnetometry and Mössbauer spectroscopy (CEMS). It could be shown that the magnetic anisotropy relative to the film normal, the, ground state magnetic moment per Fe atom and thermal spin excitations are affected by the structure of the films. In particular, a more 3-dimensional growth mode in the early state of film formation which is observed except in a certain temperature range around 300 K reduces the apparent magnetic interface anisotropy and the ferromagnetic ground state moment, and it enhances the thermal spin fluctuations and the tendency for superparamagnetic relaxation in the thinnest films.

Ferrite plating invented by the authors facilitates formation of crystalline films of spinel, (Fe, M)3O4 (M=Fe, Ni, Co, Mn, Zn, etc.), in an aqueous solution below 100 °C. This opened the door to new ferrite-film devices which use, as substrate, such non-heat-resistant materials as plastics and GaAs ICs. In this paper we describe the principle and the experimental methods of ferrite plating and report magnetic and structural properties of the films. We also describe various applications of the ferrite plating films to microwave, electrochemical and bio-medical devices.

In-situ heating in an electron microscope, together with EDX and EELS analysis, was used to characterize as-deposited amorphous and transformed garnet films. It was found that upon initial crystallization, a non-uniform precipitation of a second phase occurred, altering the local chemistry and microstructure of the transformed film. In addition, to study the transformation kinetics in more detail some experiments were conducted at slower heating rates and lower temperatures. It is hoped that the data obtained can be correlated to magnetic property measurements and contribute to the development of improved processing conditions.

Spin polarized low energy electron microscopy (SPLEEM) has been developed for the high resolution imaging of surface magnetic structure. The existing LEEM ha.s been modified by the incorporation of a. GaAs-type spin polarized electron gun. Large image contrast arises due to the spin-dependent exchange scattering, whifle the st.in-orbit contribution vanishes uniquely for the normal incidence/exit geometry used here. Pixel by pixel image subtraction for incident electron beams of opposite polarization yields precisely the spatially resolved Bragg reflection asymmetry observed in spin polarized low energy electron diffraction. The shallow electron penetration depth arising from the strong coulombic interaction is advantageous for separating surface behavior from the normally overwhelning bulk. Therefore, the use of transversally polarizedI electron beams allows the determination of in-plane surface magnetization directions. Fnrthermore, the parallel illumination and detection of SPLEEM makes it possible to image quickly with a. resolution better than 500 Å in the present configuration. A useful and direct. comparison between surface magnetic, structural, and topological features is made possible by the augmentation of the unique imaging capabilities of conventional LEEM with the magnetic sensitivity of SPLEEM. In this manner, the magnetic domain structure of a Co (0001) surface and in-situ grown Co filmns on Mo(110) have been determined.

The magnetic storage industry moved from particulate to thin fdm disks during the 1980's due to the trend toward higher density media. The disk dimensions also shrunk, from 350 mm to 95 mm and are expected to go down to 62.5 mm. The head-disk fly height will be reduced from 35 nanometers to below 10 nanometers during the coming decade. Contamination build-up on the disk, the head, and at the head-disk interface can create problems and may ultimately lead to head crashing. Therefore, it is important to build hard disk drives using very clean components. Some of the important components are the disk, the bearing, the head, the actuator, the comb, and the spindle. Hydrocarbon contamination is ubiquitous. Lubricants used can be collected by the head and may cause head print problems. Depending upon the curvature of the head and asperities on the disk, there will be head-disk interactions which can lead to smears on the disk surface. Build-up of such smears on the head and disk can reduce fly height and cause performance problems.

Static Secondary Ion Mass Spectrometry (S-SIMS) is a powerful technique used to analyze both organics (characteristic fragmentation pattern) and inorganics (by mass number, including isotopic ratio). This approach is not possible with other analytical techniques. Further, the technique is surface sensitive and the detection limit is very low. This paper discusses S-SIMS mapping of smears and head prints following contact/start/stop (CSS) testing. The roles played by individual file components in generating smears are identified. S-SIMS can also be extended to contaminant analysis on silicon wafers, printed board circuits, etc.

Tunneling stabilized magnetic force microscopy (TSMFM) is a variant of scanning tunneling microscopy (STM) where the usual rigid STM tip is replaced with a flexible magnetic tip. This method contrasts with other magnetic force microscopes based on optical or capacitive detection of cantilever deflection due to magnetic forces. Instead, the position of the flexible tunneling tip depends on both topography and magnetic forces acting on the end of the tip. The z-motion of the piezoelectric translator flexes the tip to balance the magnetic force so that the end of the tip remains a fixed tunneling distance from the sample surface. We present a review of some TSMFM images showing the recorded bit patterns on hard disk, floppy disk, and tape surfaces. The images were taken in air using STM tips made from free-standing Fe and Ni films about 1 μm thick. The image resolution of TSMFM is routinely submicrometer. We conclude that this simple modification of STM will be a valuable diagnostic tool in the magnetic recording industry.

Fe-N films with thicknesses of 500–1000 Å have been epitaxially grown on lno-2 Gao-e As(001) substrates using MBE system. Deposition atmosphere was N2 + 20%NH3. and pressure during deposition was around 1 × 10−4 Torr. Two electron guns were used in order to control nitrogen concentration of 11 at% in Fe-N films. When substrate temperature was 150 °C, an Fe1 eN2 single crystal films were found to be formed after annealing at 150 °C. When the substrate temperature was around 300 °C, Fe1 eN2. films were grown epitaxial ly on lno-2 Gao-3 As without annealing, while Fe1 eN2 could not be grown at substrate temperature higher than 350 °C because of the formation of Fe2 As caused by the reaction between substrate and Fe–N films. RHEED and XRD patterns showed that Fe1 eN2 films was grown epitaxial ly and crystal orientation of Fe1 eN2 films are Fe1 eN2 (001)//lno-2 Gaoo-eAs(001) and Fe1 eN2 [100]//lno-2 Gaoo-e As [100]. Saturation magnetic flux density of Fe1 eN2 is 2.8˜3.0T.

The interdiffusion kinetics of ultrahigh vacuum deposited Ta/Ni81Fe19 short-period multilayers films have been investigated, and changes in microstructure were related to magnetic properties. Small angle X-ray diffraction and transmission electron microscopy were used to study layer morphology evolution and interdiffusion during post-growth isothermal annealing in the temperature range 300 – 600°C. The kinetic analysis suggests that interface roughening due to grain growth, and grain-boundary mediated diffusion of Ta occurs concurrently at early anneal times in the Ni81Fe19 films. Subsequent grainboundary and lattice diffusion of Ta lead to a reduction of magnetization and increase in coercivity of Ni81Fe19.

We present new results on the magnetic properties of constrained, iron base, good quality, single-crystalline superlattices, Fe/Ru and Fe/Ir. It is shown that in the first case there are two magnetically dead layers at the interface while in the second case there is probably none. The magnetic moment of Fe is, in both superlattices, about 1.7μb. The magnetic anisotropy are opposite, in plane for Fe/Ru, perpendicular for Fe/Ir.