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 t he solid disk geometry of the device that produces a magnetic singularity a t 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.