Significance of image-charge fields on the write performance of a pole-keeper head

This paper presents a method for the computation of the magnetization and magnetic-field distributions of one transition in a perpendicular recording layer. It is used in a thick single-pole head keeper layer configuration to show that image-charge effects are significant and have a geometry-dependent impact on both height and gradient of the transition

A hysteresis model for an orthogonal thin-film magnetometer

The operation of a ferromagnetic thin-film magnetometer using the anisotropic magnetoresistance effect in a permalloy film is discussed. Measurements showed the presence of a hysteresis effect not predicted by available models. It is shown that the sensitivity of the magnetometer is predicted by applying F.S. Greene and R.B. Yarbrough's (1970) orthogonal susceptibility model, and that the hysteresis can be explained by assuming dispersion in the magnitude of anisotropy. The orthogonal susceptibility model must be evaluated numerically, accounting for a finite driving field. The effect of an inhomogeneous demagnetizing field in the film is discussed in relation to magnitude dispersion of the anisotrop

A fabrication process for electrostatic microactuators with integrated gear linkages

A surface micromachining process is presented which has been used to fabricate electrostatic microactuators. These microactuators are interconnected with each other and linked to other movable microstructures by integrated gear linkages. The gear linkages consist of rotational and linear gear structures, and the electrostatic microactuators include curved electrode actuators, comb-drive actuators, and axial-gap wobble motors. The micromechanical structures are constructed from polysilicon. Silicon dioxide was used as a sacrificial layer, and silicon nitride was used for electrical insulation. A cyclohexane freeze drying technique was used to prevent problems with stiction. The actuators, loaded with various mechanisms, were successfully driven by electrostatic actuation. The work is a first step toward mechanical power transmission in micromechanical system

The switching criterion in perpendicular magnetic recording

This paper presents a theoretical analysis of the effect of the "switching criterion", the level at which self-consistency is assumed in calculations on the perpendicular magnetic recording process. It can be proven that in a perpendicular recording configuration with an ideal keeper layer and a recording layer with a rectangular hysteresis loop, the switching criterion in stand-still recording situations is immaterial, because self-consistency is reached at all depth levels simultaneously. If either the keeper layer is absent, or the recording layer's hysteresis loop is sheared, it is shown that the higher the level at which self-consistency is assumed, the sharper the stand-still recorded transitions will be

Transcription-coupled and global genome repair differentially influence UV-B-induced acute skin effects and syste

Exposure to UV-B radiation impairs immune responses in mammals by inhibiting especially Th1-mediated contact hypersensitivity and delayed-type hypersensitivity. Immunomodulation is not restricted to the exposed skin, but is also observed at distant sites, indicating the existence of mediating factors such as products from exposed skin cells or photoactivated factors present in the superficial layers. DNA damage appears to play a key role, because enhanced nucleotide excision repair (NER) strongly counteracts immunosuppression. To determine the effects of the type and genomic location of UV-induced DNA damage on immunosuppression and acute skin reactions (edema and erythema) four congenic mouse strains carrying different defects in NER were compared: CSB and XPC mice lacking transcription-coupled or global genome NER, respectively, as well as XPA and TTD/XPD mice carrying complete or partial defects in both NER subpathways, respectively. The major conclusions are that 1) transcription-coupled DNA repair is the dominant determinant in protection against acute skin effects; 2) systemic immunomodulation is only affected when both NER subpathways are compromised; and 3) sunburn is not related to UV-B-induced immunosuppression

Simulation of the perpendicular recording process including image charge effects

This paper presents a complete model for the perpendicular recording process in single-pole-head keeper-layer configurations. It includes the influence of the image-charge distributions in the head and the keeper layer. Based on calculations of magnetization distributions in standstill situations, the model describes the relaxation process that takes place if the activated head is shifted along the recording layer, periodically switching its head field. The magnetization distributions thus derived are used in combination with a model for the readback process to calculate the readback flux and voltage pulses. For the sake of arithmetical convenience, the model was applied to a recording configuration with a thick single-pole head, but it can also be used for calculations with other head shapes, e.g. thin single-pole heads

Orthogonal thin film magnetometer using the anisotropic magnetoresistance effect

In an orthogonal thin film magnetometer a driving field oriented in the plane of a permalloy film along its hard-axis, saturates this film periodically in positive and negative direction. On return from saturation and in absence of a magnetic field component along the easy-axis, the magnetization in 50% of the film will rotate clockwise and in the remaining 50% anticlockwise giving rise to domain formation. With an easy-axis field component Hm, more than 50% will rotate in a sense determined by Hmand a net magnetization Mmwill be present as the drive field goes through zero. Hmis measured by detecting Mm. In prevlous proposals Mmis detected inductively. We propose the application of the anisotropic magnetoresistance effect by measuring either the planar Hall voltage or the resistance of the film with the dc-current at respectively 0° or 45° to the easy-axis. Expressions for the sensitivity of both the inductive and the magnetoresistive detection methods are derived, showing that the magnetoresistive method behaves better under miniaturization. With a 1 cm square permalloy film, using phase-sensitive detection of the planar Hall voltage, synchronously with the third harmonic of the drive frequency, 3×10-5V m/A sensitivity and 0.01A/m resolution have been obtained