Pole tip saturation in magnetic recording heads

Abstract

The saturation of a magnetic recording head has been studied by numerically solving for the scalar magnetic potential in a region which includes the pole tip corners. The method follows Monson in which the bulk saturation behavior provides the boundary conditions. It is shown that saturation of the pole corner primarily affects the recording field gradients and does so appreciably only when the deep-gap field exceeds one half the material saturation magnetization. The field magnitudes are only slightly affected and remain dominated by the bulk saturation. It is argued that reductions in short-wavelength recorded signal should occur when the recording medium coercivity exceeds approximately one-quarter the saturation magnetization of the head material. This condition is almost reached by the utilization of ferrite record heads ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M_{s} \cong 4-5</tex> kG) to record on high coercivity media ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_{c} \cong 1000</tex> Oe). The computation is restricted to two dimensions and the effects of losses, such as eddy currents, have not been included.