Magnetization reversal of micron-scale cobalt structures with a nanoconstriction

The magnetization reversal behavior of 20 nm thick cobalt microstructures with a nanoconstriction of variable size has been studied using magnetoresistance measurements and micromagnetic simulations. Depending on the direction of the applied field relative to the current, reversible and irreversible switching events are observed, which can be explained using micromagnetic simulations. Anisotropic magnetoresistance (AMR) is the dominant resistance contribution in the systems measured. The simulations show that instead of one sharp domain wall, which may lead to ballistic magnetoresistance (BMR), two domain walls on each side of the nanocontact precede the complete reversal. Index Terms--Cobalt, magnetic domain walls, magnetoresistance, micromagnetic simulations, nancontacts.