The dynamic surface magnetic response and flux propagation in arrays of multilayer magnetic thin-film stripes subject to high frequency magnetic fields has been studied using scanning Kerr imaging and a high frequency permeameter respectively. Scanning Kerr Images of the regions of surface response to a uniform oscillating magnetic field of up to 2 Oc between 1 and 50 MHz identify the domain state and surface permeability of the multilayer films. Transitions among the expected easy-axis laminated, hard axis, closure domain and a new complex domain state are observed as the total and magnetic layer thicknesses, stripe widths and field history are changed. As expected, the high frequency magnetic response of single layer films is dominated by magnetization rotation at low field, while closure domain wall motion becomes significant above the coercivity. Easy-axis domain state multilayer films, in narrow structures those films with magnetic layers a few hundredÅngströms thick or less, exhibit a uniform high permeability over the entire surface of the film. The dynamics of the new complex domain pattern seen in narrow multilayer films with thicker magnetic layers is complicated, with a blotchy, hysteretic magnetic response from the center of the strip and a immobile, mostly hard-axis oriented region along the edge.

The influence of the composition of plated Permalloy on the resulting magnetic domain structure in the upper yoke of inductive thin-film magnetic recording heads has been investigated. The response of the magnetization from four otherwise similar thin-film heads, ranging in iron content from 18 to 21% by weight, has been imaged by means of a scanning magnetooptic photometer. Radially compressive (and/or circumferentially tensile) strain is shown to exist in each of these heads about the rear magnetic closure, yielding a transition from radial to circumferential domain structures across the range of compositions. Mechanisms for the conduction of magnetic flux in each of these structures are demonstrated at 1 and 20 MHz

Thin-film disks with various orientation ratios (OR) ranging from 0.5 to 4.3 were fabricated by sputter deposition of CoPtCr with Cr underlayers onto preheated NiP/Al-Mg disks. The recording characteristics of these disks were investigated using a thin-film head. The isolated pulse signal amplitude-to-media noise ratio (So/N) increased when OR was increased from 0.5 to 1 and then remained relatively constant for OR⩾1. An improvement of about 10 dB in overwrite of the disks with OR>1 was observed