A simulation of magnetic recording on coarsely granular media

Abstract

Abstrad -The superparamagnetic effect dictates a lower limit to the size of magnetic grains in the recording medium. At very high areal densities each bit of information will thus be recorded on relatively few magnetic grains. Since the grains have random positions and sizes, there will be large statistical fluctuations or noise on the recovered signal. Modelling the media grains as random Voronoi regions, we simulate the process of writing, reading, detection and error-correction. Although the signal-tonoise ratio is very poor, we find that it possible in the simulation to recover data reliably with as few as four grains per bit.

Readback model for double layer perpendicular recording media

“…The grains are generated using a uniform random distribution of seed points in the film plane. 6 The average grain diameter and standard deviation of grain sizes are chosen to be the same as those from the experimental media studied. The magnetization direction in each grain is assumed to be in the perpendicular direction; therefore, only two magnetization directions, 0°or 180°relative to the perpendicular axis, are possible.…”

“…The advantage this grain configuration is that it is a good representation of real media, which allows us to have a better media noise model. 6,7 In this article, the model, based on reciprocity theory, uses closed form expressions for the potential around the magnetoresistance ͑MR͒ head, as previously derived, 5 to obtain the readback signal from both continuous media with perfect arctangent transitions and granular media. In Voronoi media, we assume each grain to be single domain with uniaxial anisotropy.…”

Effect of crystalline disorder on magnetic switching in small magnetic cells

“…Since the easy axis direction defines the orientation of the coordinate frame relative to which the Stoner-Wohlfarth astroid is measured, it is clear even without calculation that the energy density (16) leads for each K and γ again to an ideal astroid that is rotated by the angle γ and changed in size by a factor K/K 1 (if magnetic fields are still measured in units of 2K 1 /M s , the normalization used in eqs. (14,15)). In the explicit form of the stability boundary derived again from ∂ θ E(θ) = 0 = ∂ 2 θ E(θ),…”

Analysis and optimization of terabit magnetic recording systems limited by down-track and cross-track write field gradients

“…These assessments vary in the degree to which head fields limit the projected capability of the technology. For example, Wood et al [1] considered a system in which neither the magnitude of the head field nor its gradients were explicitly considered as a limitation. Grain size was considered as an independent variable, however, which corresponds directly to medium anisotropy field, H k , if a condition of fixed thermal stability is imposed.…”

“…As perpendicular recording approaches commercialization, many attempts have been made to assess the potential of the technology and its [1][2][3][4][5][6][7][8][9][10]. These assessments vary in the degree to which head fields limit the projected capability of the technology.…”