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Magneto Optic Hysteresigraph

IP.com Disclosure Number: IPCOM000098545D
Original Publication Date: 1959-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Hart, DM: AUTHOR

Abstract

A technique is described which relates to a magneto-optic hysteresigraph for observing the hysteresis loop and determining the wall velocity or switching speed of a ferromagnetic film by use of the Kerr or Faraday magneto-optic effect.

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Magneto Optic Hysteresigraph

A technique is described which relates to a magneto-optic hysteresigraph for observing the hysteresis loop and determining the wall velocity or switching speed of a ferromagnetic film by use of the Kerr or Faraday magneto-optic effect.

In utilizing the Kerr magneto-optic effect the vector of polarization of plane polarized light is rotated when reflected by a magnetized material. An incident beam of polarized light covers the entire surface area of the upper face of the magnetic material. The reflected light is passed through an analyzer with only the light reflected from areas of unchanged magnetization being allowed to reach a photomultiplier tube. The voltage output of the photomultiplier tube is proportional to the amount of light reaching it and, therefore, is proportional to the amount of unchanged flux. The entire switching phenomena is picked up by the photomultiplier tube and displayed on the oscilloscope in the form of a hysteresis loop or as a direct display of the film transition.

The Faraday magneto-optic effect could also be used by passing the light through the magnetic material rather than reflecting it from the surface.

Observation of the high speed transition of the magnetic film by use of the photomultiplier tube and the oscilloscope provides new information not obtainable by conventional pickup techniques which indicate only a rate of change rather than the actual transition.

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