Synthetic CoFeB/Ru/NiFe free layer on MgO barrier layer for spin transfer switching

Abstract

In order to study the application potential of spin transfer switching in magnetic tunnel junctions (MTJs), a synthetic parallelly coupled layered structure such as a hard CoFeB/Ru/soft NiFe layers deposited on a MgO layer is investigated. The magnetic coupling between the layers is maintained · · after post-annealing at 300 °C, while annealing at 350 °C reduces the coupling strength. The observation of spin transfer switching in the junction indicates that parallel-to-antiparallel transition does not occur when the applied current pulse width is in the sub-millisecond range, which is far from the precessional range. This result indicates that spin transfer from NiFe to CoFeB might affect the dynamics of CoFeB magnetization. © 2010 IOP Publishing Ltd.