The impedance of magnetic recording heads at high frequencies is reduced by making the gap spacer of conducting material, because eddy currents in this conductor lower the permeance of the gap region. The traditional formulae for the complex permeability vs frequency of a conducting lamination (as used in transformer design) apply within the gap area. The formulae involve spacer initial permeability, resistivity and the gap depth which corresponds to the usually-used lamination thickness. Measurements of impedance vs frequency of a large -model- head verify the theory.
Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.