Effects of film discontinuities on sense voltage in magnetic plated wires

The effects of physical surface defects on the sense output voltage of magnetic plated wires is investigated from an experimental and analytical point of view. The one-to-one correspondence between such defects and resulting dropouts is shown experimentally, and the mechanism of memory mode failure is shown to be due to an increased write threshold for a bit containing a defect. Various types of scratches and cavities are investigated for their effects on the storage properties of the bit, and it is shown that the significant factor involved is the length of circumferential, easy axis flux closure path interrupted by the defect. A model is derived which relates defect size to observed voltage decreases.