Survey and Review
1
Consider the fact that you can put your entire music collection on your portable mp3 player and you begin to realize what a tremendous amount of data is being stored in its tiny disk drive. How is it possible that data can be so efficiently stored in a magnetic storage device? The answer is ferromagnetism. Progress in storage technology follows Kryder’s law, which is akin to the more familiar Moore’s law, governing the performance of CPUs. The storage capacity of disk drives, measured by areal density, has increased exponentially in the past 20 or so years. At the time of this writing, areal density of 110 Gbits/square inch is common. A new storage format, called perpendicular format, is capable of areal density of 245 Gbits/square inch. Ferromagnetism, the subject of the article by Martin Kruˇ z´ ık and Andreas Prohl, is modeled by a continuum theory called micromagnetics. The mathematics of micro- magnetics is complex and beautiful, exhibiting rich and surprising behavior. The article introduces the reader to the models of micromagnetics, their mathematical analyses, and simulation methods for them. The authors show that despite great progress in this field, much still needs to be understood. Perhaps the key to quantifying the the- oretical limit of magnetic storage capacity lies in the mathematics of micromagnetics. Mathematics might also provide guidance on how one can achieve this limit in practical devices. Fadil Santosa Section Editor [email protected] 437 Downloaded 11/18/14 to 130.113.86.233. Redistribution subject to SIAM license or copyright; see http://www.siam.org/journals/ojsa.php
Transcript of Survey and Review
Consider the fact that you can put your entire music collection on your portablemp3 player and you begin to realize what a tremendous amount of data is being stored inits tiny disk drive. How is it possible that data can be so efficiently stored in a magneticstorage device? The answer is ferromagnetism. Progress in storage technology followsKryder’s law, which is akin to the more familiar Moore’s law, governing the performanceof CPUs. The storage capacity of disk drives, measured by areal density, has increasedexponentially in the past 20 or so years. At the time of this writing, areal density of110 Gbits/square inch is common. A new storage format, called perpendicular format,is capable of areal density of 245 Gbits/square inch.
Ferromagnetism, the subject of the article by Martin Kruzık and Andreas Prohl,is modeled by a continuum theory called micromagnetics. The mathematics of micro-magnetics is complex and beautiful, exhibiting rich and surprising behavior. The articleintroduces the reader to the models of micromagnetics, their mathematical analyses,and simulation methods for them. The authors show that despite great progress inthis field, much still needs to be understood. Perhaps the key to quantifying the the-oretical limit of magnetic storage capacity lies in the mathematics of micromagnetics.Mathematics might also provide guidance on how one can achieve this limit in practicaldevices.
Fadil SantosaSection Editor
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