Modeling of enlarged back gaps in vertical giant magnetoresistance read heads

To fully exploit the capability of vertical head sensors, it is necessary t o increase the gap immediately after the front contact region located at th e air bearing surface. Because of fringing of the flux as it leaves the sen sor and passes to the shields, the effective gap is less than the physical gap. An analysis has been performed using an electrical, SPICE, analog mode l for the field equations to determine the relationship between the change in the physical gap and the effective gap in terms of the signal decay alon g the sensor [A. V. Pohm, R. S. Beech, J. M. Anderson, and W. C. Black, IEE E Trans. Magn. 33, 2392 (1997)]. Three enlarged half gaps were considered: one with an abrupt increase, one with a slope of two, and one with a slope of one. The analysis considered mostly back gaps which were ten times large r than the front gaps, going from 0.1 to 1.0 mu m, for example. The results show an abrupt step yields an effective slope of 0.9 and a physical step w ith a slope of 1 yields an effective slope of 0.75. The effective slopes ar e being used to more accurately model the decay of signal flux along vertic al head sensors. (C) 1999 American Institute of Physics. [S0021-8979(99)311 08-7].