Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

High Resolution Dynamic Magnetic Domain Readout

IP.com Disclosure Number: IPCOM000042736D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 4 page(s) / 39K

Publishing Venue

IBM

Related People

Kay, E: AUTHOR [+2]

Abstract

Ability to observe magnetic domains on thin films on substrates of any thickness statically or at very high frequency - future progress in the field of magnetic recording may well be enhanced by new methods for viewing small magnetic domains at high speed. For further development of such schemes, it is desirable to be able to observe the dynamic and static behavior of domain patterns with a spatial resolution of less than 0.5 mm and in a time of less than 10-6 sec. Furthermore, it should be possible to accomplish this with magnetic materials which are deposited onto a nontransparent substrate and sometimes with a film thickness of less than 500 A .

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 31% of the total text.

Page 1 of 4

High Resolution Dynamic Magnetic Domain Readout

Ability to observe magnetic domains on thin films on substrates of any thickness statically or at very high frequency - future progress in the field of magnetic recording may well be enhanced by new methods for viewing small magnetic domains at high speed. For further development of such schemes, it is desirable to be able to observe the dynamic and static behavior of domain patterns with a spatial resolution of less than 0.5 mm and in a time of less than 10-6 sec. Furthermore, it should be possible to accomplish this with magnetic materials which are deposited onto a nontransparent substrate and sometimes with a film thickness of less than 500 A . The dynamic techniques practiced so far for viewing magnetic domains are based on the coupling of electromagnetic waves to the magnetization (Faraday or Kerr effect), or on the Lorentz deflection of electrons in the magnetic stray field above the domain walls or inside the sample (Lorentz microscopy). Both approaches yield little contrast, in part obscured by nonmagnetic topological features, and therefore require long observation times. Also, they cannot cope with thin magnetic films [1] on thick, nonmagnetic substrates. It has previously been proposed (2) that magnetic domains can be detected by spin selective scattering of electrons on magnons (3). This has the advantage that one can deal with very thin samples on reasonably well conducting substrates, and that one may have a high spatial resolution by focusing the primary electron beam into a spot of diameter 100 A on the sample. However, the scheme as proposed in (2) is slow. It takes more than 1 msec to determine the direction of magnetization (4). Clearly, this is too slow by at least 3 orders of magnitude as a means of detecting domain switching in, for example, reading heads at frequencies practiced today. It is also much too slow for following magnetization switching. Furthermore, the high energy density of the electron beam may cause radiation damage in a thin sample. The apparatus described below is designed to overcome these and other limitations. To our knowledge, no other dynamic domain observation technique exists for thin magnetic layers with the resolution and speed covered by the present technique. Furthermore, it should be recognized that, whereas the combination of phenomena and associated apparati leading to the final embodiment of the method has never been assembled anywhere, each of the phenomena utilized has been independently and quantitatively studied. Described here is an apparatus for viewing magnetic domains or bits that (i) is extremely fast, (ii) may have spatial resolution of less than 0.5 mm, (iii) is not disturbed by topological features of the sample, and (iv) permits probing extremely thin samples on a substrate of any thickness. The new apparatus also provides a very fast way to retrieve the information stored in a magnetic pattern irrespective of whet...