Normal and inverse current-induced magnetization switching in a single nanopillar

Abstract

The authors report on current-induced magnetization switching (CIMS) in single-crystalline nanopillars. Fe(14nm)∕Cr(0.9nm)∕Fe(10nm)∕Ag(6nm)∕Fe(2nm) multilayers are deposited by molecular-beam epitaxy. The central Fe layer is coupled to the thick one by interlayer exchange coupling over Cr, while the topmost Fe layer is decoupled. Nanopillars with 150nm diameter are prepared by optical and e-beam lithographies. The opposite spin scattering asymmetries of the Fe∕Cr and Fe∕Ag interfaces enabled the authors to observe normal and inverse CIMS for the two subsystems, which are combined in a single device. At high magnetic fields, steplike resistance changes are measured at positive currents and are attributed to current-driven magnetic excitations.