Determining vortex chirality in ferromagnetic ring by lateral nonlocal spin valve

Abstract

We demonstrate detecting chirality of vortex state in a magnetic ring by lateral nonlocal spin-valve (NLSV) measurement. A Permalloy (Py) ring, a Py narrow wire, and copper contacts were used as spin injector, detector, and the normal-metal diffusive channel, respectively. By comparing the anisotropic magnetoresistance loop of the individual ring with NLSV loop, the vortex chirality and the related switching field of the ring can be determined. Both onion-to-vortex transition field and vortex chirality were found to alternate in both the same and different current probe arrangements on the magnetic ring. (C) 2008 American Institute of Physics.