R.f.-sputtered Co-Cr layers for perpendicular magnetic recording I: Structural properties

Lodder, J.C.; Wielinga, T.; Worst, Jgf

doi:10.1016/0040-6090(83)90493-5

Cited by 101 publications

(22 citation statements)

References 15 publications

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“…These small grains tend to coalesce, depending on temperature, resulting in tapered grains up to 1 pm or more in diameter. Lodder et al 19 suggested a plausible explanation for this coalescence phenomenon. Amorphous substrates of metals or chemically vapour deposited SiO2 induce growth of broad (a few tenths of a micron wide) columns extending through the film thickness, probably (00i) oriented.…”

Section: Discussionmentioning

confidence: 99%

“…This taperwise growth is not explained by the "survival of the fastest" model, since layers are highly oriented from the very first stage as observed by XRD. The thermodynamically driven coalescence mechanism suggested by Lodder et al 19 provides a plausible explanation. Dense and "single-crystal-like" films are grown, probably (001) oriented.…”

Section: Scanning Electron Micrographsmentioning

confidence: 99%

“…In films that are well oriented from the very first stage, the "survival of the fastest" model cannot explain an increase in grain size with film thickness (taperwise grain growth). Lodder et al 19 suggest a thermodynamically driven coalescence of crystallites (grain boundary movement) during film growth, as an explanation for this frequently observed phenomenon.…”

Section: Oriented Growthmentioning

confidence: 99%

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R.f. planar magnetron sputtered ZnO films I: Structural properties

1991

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The structural properties of r.f. planar magnetron sputtered ZnO films are studied as a function of deposition parameters: substrate type, substrate temperature, sputter gas pressure, growth rate and sputtering power.These films are applied as piezoelectric transducers in micromechanical sensors and actuators. The electric properties, and consequently the piezoelectric behaviour, depend strongly on the structural properties of the layers.All films are polycrystalline. The individual grains are highly oriented with their crystallographic c axis perpendicular to the substrate. Crystalline substrates such as silicon or SiO2 induce a growth of small grains, a few hundredths of a micron wide and long. Amorphous substrates such as metals or amorphous SiO2 induce a growth of broad columnar grains extending through the film thickness and a few tenths of a micron wide. Trends in density and grain size are in agreement with Thornton's structure zone model.

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Section: Discussionmentioning

confidence: 99%

Section: Scanning Electron Micrographsmentioning

confidence: 99%

Section: Oriented Growthmentioning

confidence: 99%

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R.f. planar magnetron sputtered ZnO films I: Structural properties

1991

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“…Our films consist of conically shaped crystals or columns with c-axis textured hcpstructure (Lodder et al 1983). The crystal or column diameter increases almost as the square root of the film thickness.…”

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The magnetic domain structure of CoCr layers studied by neutron depolarisation

Hemmes

Lodder

Rekveldt

et al. 1984

J. Phys. D: Appl. Phys.

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Abstract. The domain structure of relatively thick RF-sputtered CoCr (81 : 19 at 9%) layers with a columnar morphology in the range of thickness 1-5 pm was investigated using a polarised neutron beam. On the basis of the results a model of straight domains running through the entire film thickness has to be rejected. Arguments are given for a serpentinelike domain structure with a domain width about the same as the column diameter (0.1-0.3 pm), resulting in a 'chain of columns' model. Sputtered CoCr layers have already been applied as a perpendicular recording medium with extremely high density (Iwasaki 1980). The morphology and crystal structure and therefore the magnetic properties of the film depend strongly on the deposition and growth conditions.Our films consist of conically shaped crystals or columns with c-axis textured hcpstructure (Lodder et al 1983). The crystal or column diameter increases almost as the square root of the film thickness. In order to understand the magnetisation process, domain studies are of great importance. If the exchange force is restricted to the columns the domain size coincides with the crystal diameter. The columns will act as single domain particles and a rotational switching mechanism is to be expected for the magnetisation process. In this case the domain structure is determined by a minimum of the magnetostatic energy and will appear as a kind of checkerboard pattern formed by the individual columns. In the case of a continuous model, where the exchange forces extend over the crystal boundaries, the magnetisation process is due to domain wall motion which is more or less hindered by the column boundaries.The domain dimensions of both particle and continuous models are too small to be observed by Kerr microscopy or the Bitter technique. The most suitable method for observing small domains is Lorentz transmission electron microscopy. A 1 MeV microscope has to be used for observing CoCr layers thicker than 0.1 pm, up to a maximum of 0.3 pm Iwasaki 1982, Grundy andAli 1983). A specially designed sample stage to exclude an external perpendicular field from the specimen during domain observations is essential Iwasaki 1982, Ohkoshi andKusuda 1983).Different domain configurations with in-plane magnetisation are observed in thin (<60 nm) CoCr layers (Grundy and Ali 1983, Ohkoshi and Kusuda 1983, Wielinga 1983. This can be explained by variations in the preparation methods. None of these films have a well oriented hcp c-axis. For a good textured layer (Co77Cr23), with a

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“…The small changes can be explained by reversible rotation of regions with in-plane anisotropy [46], which have no perpendicular anisotropy.…”

Section: Anomalous Hall Effect Measurementsmentioning

confidence: 99%

Magnetic structures in CoCr media for perpendicular magnetic recording

Lodder

1996

Journal of Magnetism and Magnetic Materials

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High bit densities have been demonstrated in longitudinal as well as in perpendicular magnetic recording. For the latter an area density of more than 12 Gbit/in 2 has been obtained in a sputtered Co-Cr-Ta hard disk with a soft magnetic underlayer recorded with a special single pole head. In this paper the role of microstructure and morphology in relation to the compositional separation is discussed. Very sensitive anomalous Hall measurements have been performed from submicron Co-Cr samples to obtain more detail information about the reversal characteristics of the material. The results obtained have been used in our model for micromagnetic simulations. One of the conclusions is that most of the magnetic entities reversing their magnetisations are much smaller than the volume of one Co-Cr column.

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R.f.-sputtered Co-Cr layers for perpendicular magnetic recording I: Structural properties

Cited by 101 publications

References 15 publications

R.f. planar magnetron sputtered ZnO films I: Structural properties

R.f. planar magnetron sputtered ZnO films I: Structural properties

The magnetic domain structure of CoCr layers studied by neutron depolarisation

Magnetic structures in CoCr media for perpendicular magnetic recording

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