Bias field and end effects on the switching thresholds of “pseudo spin valve” memory cells

It is shown experimentally for 0.4 micron wide “pseudo spin valve” memory cells that a bias field across an element significantly increases or decreases the switching threshold of the thicker films which store the data depending on whether the bias aids or opposes the sense field. This thick layer threshold shift has been modeled with torque equations by treating the magnetic layers as near single domains that strongly interact because of their proximity. Experimentally, it is shown that the length of the end contact regions have a large influence on the threshold field if the contact regions are long enough to hold a domain wall. Short contact regions are a necessary but not sufficient condition to ensure that trapping of a wall at the ends of the elements does not occur