Low resistance spin-dependent magnetic tunnel junction with high breakdown voltage for current-induced-magnetization-switching devices

Spin-dependent magnetic tunnel junctions (MTJs) with pure AlOx barriers were fabricated by one-step and two-step natural oxidation processes, respectively (500mTorr 20min; 500mTorr 5min and 1Torr 10min). Preoxidized Al barrier thickness varies from 5to7A. In this work, a multilayer structure with a low resistance of 0.8Ω∕sq and rms of 1.54A was developed as the bottom electrode. MTJs with the following structure Ta(30A)∕NiFe (40A)∕MnIr (80A)∕CoFe (30A)∕Al+oxidation∕CoFe (30A)∕NiFe (40A)∕Ta (200A) were magnetically annealed at 230°C for 30min to set the exchange bias field in the MnIr∕CoFe bilayer. Resistance×area (RA) products varying from 0.5to13Ωμm2 were achieved with tunneling magnetoresistance ratios varying from 8% to 18%. Breakdown voltages higher than 450mV were obtained for a sample with RA 0.5Ω×μm2, which allows a current of 9×107A∕cm2 to flow through the MTJ without damaging the barrier. Current-induced magnetization switching based on spin transfer or spin torque effect with a current density o...

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