Mathematical Analysis of Two Unequal Collinear Cracks in a Piezo-Electro-Magnetic Media

Density waves in the nature of those proposed by B. Lindblad are described by detailed mathematical analysis of collective modes in a disk-like stellar system. The treatment is centered around a hypothesis of quasi-stationary spiral structure. We examine (a) the mechanism for the maintenance of this spiral pattern, and (b) its consequences on the observable features of the galaxy.

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Transmission Electron Microscopy of oriented Co84Cr14Ta2 thin films for longitudinal magnetic recording

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088099 ◽

1991 ◽

Vol 49 ◽

pp. 756-757

Author(s):

T. P. Nolan

Keyword(s):

Thin Film ◽

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Low Cost ◽

Low Noise ◽

Information Storage ◽

High Coercivity ◽

Magnetic Alloy ◽

Magnetic Media ◽

Transmission Electron

Thin film magnetic media are being used as low cost, high density forms of information storage. The development of this technology requires the study, at the sub-micron level, of morphological, crystallographic, and magnetic properties, throughout the depth of the deposited films. As the microstructure becomes increasingly fine, widi grain sizes approaching 100Å, the unique characterization capabilities of transmission electron microscopy (TEM) have become indispensable to the analysis of such thin film magnetic media.Films were deposited at 225°C, on two NiP plated Al substrates, one polished, and one circumferentially textured with a mean roughness of 55Å. Three layers, a 750Å chromium underlayer, a 600Å layer of magnetic alloy of composition Co84Cr14Ta2, and a 300Å amorphous carbon overcoat were then sputter deposited using a dc magnetron system at a power of 1kW, in a chamber evacuated below 10-6 torr and filled to 12μm Ar pressure. The textured medium is presently used in industry owing to its high coercivity, Hc, and relatively low noise. One important feature is that the coercivity in the circumferential read/write direction is significandy higher than that in the radial direction.

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Using the scanning electron microscope for failure analysis of high density magnetic media

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126755 ◽

1987 ◽

Vol 45 ◽

pp. 392-393

Author(s):

Evelyn R. Ackerman ◽

Gary D. Burnett

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Failure Analysis ◽

High Density ◽

Magnetic Media ◽

Specific Data ◽

Retrieval Systems ◽

Operating Environments ◽

The Media ◽

Scanning Electron

Advancements in state of the art high density Head/Disk retrieval systems has increased the demand for sophisticated failure analysis methods. From 1968 to 1974 the emphasis was on the number of tracks per inch. (TPI) ranging from 100 to 400 as summarized in Table 1. This emphasis shifted with the increase in densities to include the number of bits per inch (BPI). A bit is formed by magnetizing the Fe203 particles of the media in one direction and allowing magnetic heads to recognize specific data patterns. From 1977 to 1986 the tracks per inch increased from 470 to 1400 corresponding to an increase from 6300 to 10,800 bits per inch respectively. Due to the reduction in the bit and track sizes, build and operating environments of systems have become critical factors in media reliability.Using the Ferrofluid pattern developing technique, the scanning electron microscope can be a valuable diagnostic tool in the examination of failure sites on disks.

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High-resolution scanning electron microscopy of thin-film magnetic media of magnetic recording disk

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131309 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1334-1335

Author(s):

K. Ogura ◽

H. Nishioka ◽

N. Ikeo ◽

T. Kanazawa ◽

J. Teshima

Keyword(s):

Thin Film ◽

Fine Structure ◽

High Resolution ◽

Magnetic Recording ◽

High Performance ◽

Magnetic Hysteresis ◽

Grain Structure ◽

Magnetic Media ◽

Cross Sectional ◽

Resolution Observation

Structural appraisal of thin film magnetic media is very important because their magnetic characters such as magnetic hysteresis and recording behaviors are drastically altered by the grain structure of the film. However, in general, the surface of thin film magnetic media of magnetic recording disk which is process completed is protected by several-nm thick sputtered carbon. Therefore, high-resolution observation of a cross-sectional plane of a disk is strongly required to see the fine structure of the thin film magnetic media. Additionally, observation of the top protection film is also very important in this field.Recently, several different process-completed magnetic disks were examined with a UHR-SEM, the JEOL JSM 890, which consisted of a field emission gun and a high-performance immerse lens. The disks were cut into approximately 10-mm squares, the bottom of these pieces were carved into more than half of the total thickness of the disks, and they were bent. There were many cracks on the bent disks. When these disks were observed with the UHR-SEM, it was very difficult to observe the fine structure of thin film magnetic media which appeared on the cracks, because of a very heavy contamination on the observing area.

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Computing cell tractions from particle displacements on silicone rubber substrata

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168542 ◽

1994 ◽

Vol 52 ◽

pp. 162-163

Author(s):

Tim Oliver ◽

Akira Ishihara ◽

Ken Jacobsen ◽

Micah Dembo

Keyword(s):

Plane Stress ◽

Linear Elasticity ◽

Silicone Rubber ◽

Mathematical Analysis ◽

Elastic Recovery ◽

Video Images ◽

Cell Traction Forces ◽

Latex Beads ◽

Cell Traction ◽

Better Than

In order to better understand the distribution of cell traction forces generated by rapidly locomoting cells, we have applied a mathematical analysis to our modified silicone rubber traction assay, based on the plane stress Green’s function of linear elasticity. To achieve this, we made crosslinked silicone rubber films into which we incorporated many more latex beads than previously possible (Figs. 1 and 6), using a modified airbrush. These films could be deformed by fish keratocytes, were virtually drift-free, and showed better than a 90% elastic recovery to micromanipulation (data not shown). Video images of cells locomoting on these films were recorded. From a pair of images representing the undisturbed and stressed states of the film, we recorded the cell’s outline and the associated displacements of bead centroids using Image-1 (Fig. 1). Next, using our own software, a mesh of quadrilaterals was plotted (Fig. 2) to represent the cell outline and to superimpose on the outline a traction density distribution. The net displacement of each bead in the film was calculated from centroid data and displayed with the mesh outline (Fig. 3).

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Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151027 ◽

1993 ◽

Vol 51 ◽

pp. 1038-1039 ◽

Cited By ~ 1

Author(s):

G.A. Bertero ◽

R. Sinclair

Keyword(s):

Remanent Magnetization ◽

Strong Influence ◽

Uniaxial Anisotropy ◽

Magnetic Coupling ◽

Recording Media ◽

Magnetic Media ◽

Signal To Noise ◽

Out Of Plane ◽

Longitudinal Recording ◽

The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

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