Current-induced excitations in single cobalt ferromagnetic layer nanopillars

Abstract

Current-induced spin wave excitations were studied in single Cu/Co/Cu ferromagnetic layer nanopillars. These excitations were studied as a function of Co layer thickness at low temperatures for large applied fielded perpendicular to the layers. Current-induced excitations for asymmetric junctions were observed at high current densities for only one polarity whereas they were absent at the same current densities in symmetric junctions. These measurements were performed in high magnetic fields in the field perpendicular to the plane geometry at 4.2 K. The results show that in asymmetric junctions the critical currents increases with Co layer thickness.