Heads for high-density magnetic tape recording

Various limitations in the design of recording heads are reviewed. Track definition and gap length, the need for small heads and possible improvements in the shape of heads, coil chambers and magnetic flux guides, and the requirements for the materials to be used in metal-in-gap heads and sandwich heads are considered. With respect to future development, it is predicted that higher density will require shorter gaps (the present gaps can be made shorter without much effort), higher B_s values for writing at long wavelengths, and higher μ for efficient reading with short-gapped heads