Structure of the double-barrier MTJs with a thermal barrier in the bottom electrode (left), and TEM picture of the fabricated junctions, from where the quality of both oxide barriers and both Ru spacers of the top and bottom SAF layers could be investigated. Vacuum breaks that occurred during stack fabrication are indicated by .
Dependence of the film resistivity on the annealing temperature indicating the transition from amorphous to crystalline above 270 °C. The resistivity of and 1000-Å-thick Al films is also shown. The inset shows the AFM scan of an Al 150 Å stack, with a rms roughness of 0.28 nm.
VSM curve of the complete double-barrier junction stack annealed at 280 °C (structure as in Fig. 1, grown above the GeSbTe film). One of the insets shows the temperature dependence of the storage layer exchange coupling, from which a blocking temperature of is obtained.
(a) Transfer curves for the two writing states, measured before and after thermally assisted switching. The current pulse was applied under an external field of . The switching mechanism (from the transfer curve at positive shift into negative shift) is illustrated in (b), where the junction resistance is monitored for several points of the transfer curve, after the application of a current pulse.
(a) Write current density and (b) write power density (, with measured at ) dependence on the junction area, obtained for double junctions with or without GeSbTe thermal barriers.
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