Observation of spin-transfer switching in deep submicron-sized and low-resistance magnetic tunnel junctions

The spin-transfer effect has been studied in magnetic tunnel junctions (PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe) with dimensions down to 0.1x0.2 mum(2) and resistance-area product RA in the range of 0.5-10 Omega mum(2) (DeltaR/R=1%-20%). Current-induced magnetization switching is observed with a critical current density of about 8x10(6) A/cm(2). The attribution of the switching to the spin-transfer effect is supported by a current-induced DeltaR/R value identical to the one obtained from the R versus H measurements. Furthermore, the critical switching current density has clear dependence on the applied magnetic field, consistent with what has been observed previously in the case of spin-transfer-induced switching in metallic multilayer systems. (C) 2004 American Institute of Physics.