Current-driven reversal in annular vertical giant magnetoresistive devices

Experiments are reported that demonstrate the asymmetric switching behavior reported earlier in vertical giant magnetoresistance devices arises from the solid disk geometry of the device that produces a magnetic singularity at the disk center. Annular devices having a 0.1 mum center hole and 0.5 mum outer diameter are shown to switch symmetrically with an Amperian field. (C) 2001 American Institute of Physics.