Design of planar coils of minimum resistance for magnetic recording devices

Magnetic data stored on computer hard disk drives is read and written by small electromagnets on read/write heads that pass over the surfaces of the spinning hard disks [7]. These electromagnets are composed of magnetic alloy cores with wire coils wrapped around them. When an electric current is sent to the coil, a magnetic field is induced in the ferrite core, and data is written to the disk by changing the magnetization of data bits on the disk. One class of read-write heads, called thin-film heads, uses a two-dimensional spiral path of conducting material on an insulating substrate as the induction coil surrounding the horseshoe-shaped ferrite core (see Figure 1).