Measurement of the switching properties of a regular 2D array of Preisach-type particles (abstract)

Abstract

The original Preisach model of magnetic hysteresis assumes an assembly of single domain particles, each having a rectangular hysteresis loop. The loops are characterized by up and down switching fields. The halfwidth of the loop is the coercivity Hc of the given particle. The loops might be shifted depending on the magnetic state of the environment, described by an effective interaction field, Hi. In the present work the switching properties of an artificially structured, highly uniaxial, magneto-optic garnet film (courtesy of R. Belt, AIRTRON), corresponding to the assumptions of the original Preisach model, are investigated. In this case the parameter identification is straightforward. The garnet film is etched into 42 μm rectangular pixels, separated by 15 μm grooves. Each pixel has a rectangular hysteresis loop. Up and down magnetized pixels give a black and white contrast due to Faraday effect. Magnetization can be measured by counting the number of pixels switched in a given field. The distribution of the coercive field has been obtained by measuring individual loops on each of several hundred pixels in an optical magnetometer. The average Hc=265±99 Oe, Hi=0±26 Oe. The interaction field has been measured on the same pixel, depending on the magnetization state of the nearest neighbor pixels. The contribution to Hi of oppositely magnetized pixels is dHi/dn=26 Oe/pixel. These data are compared to macroscopic hysteresis loops measured in VSM.