Current Driven Oscillation And Switching In Co/Pd Perpendicular Giant Magnetoresistance Multilayer

Spin torque transfer (STT) induced magnetization oscillation and switching in metallic spin valves with Co/Pd electrodes of perpendicular magnetic anisotropy are demonstrated. The bottom Co/Pd multilayer, acting as a perpendicular spin-polarizing/reference layer, is relatively thick with a strong perpendicular anisotropy and a perpendicular switching field of 8 kOe. An in-plane spin valve is placed on the top for reading back magnetization oscillation of the middle Co layer, whose thickness is varied from 6 to 30 angstrom. When the middle Co layer is thin, current driven magnetization switching is observed. When the middle Co layer is relatively thick, perpendicular spin torque oscillation is clearly observed with oscillating frequency at 4 GHz. STT-included micromagnetic modeling has been performed which predicts the exact observed behavior and illustrates the significance of magnetization configuration of the Co layer on determining STT-induced dynamics. (C) 2011 American Institute of Physics. [doi:10.1063/1.3540415]