Apparent Spin Polarization Decay in Cu-DustedCo/Al2O3/CoTunnel Junctions

Abstract

Co/Al2O3/Co magnetic tunnel junctions with an interfacial Cu layer have been investigated with in situ growth characterization and ex situ magnetotransport measurements. Cu interlayers grown on Co give an approximately exponential decay of the tunneling magnetoresistance with xi approximately 0.26 nm while those grown on Al2O3 have a decay length of 0.70 nm. The difference in decay lengths can be explained by different growth morphologies, and in this way clarifies a present disagreement in the literature. For monolayer coverage of Cu, we show that the tunneling spin polarization is suppressed by at least a factor of 2 compared to Co and beyond approximately 5 ML it becomes vanishingly small.

Spin injection at remanence into III-V spin light-emitting diodes using (Co/Pt) ferromagnetic injectors

“…This results from the reduced extent of the tunneling branching of the corresponding wave function at barrier/metal interfaces with a characteristic length hardly exceeding one or two atomic planes inside the metallic electrode. 80,81 Finally, our experiment performed on sample C seems to demonstrate a (ferromagnetic) interlayer exchange coupling between the Co/Pt multilayer and the thin Fe layer mediated through the 0.6-nm-thick Pt, as evidenced in a recently in the case of Pd/NiFe multilayers. 82 …”

Role of the barrier in spin-dependent tunneling addressed with superconductor spectroscopy

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Inherent temperature effects in magnetic tunnel junctions

“…Figure 4 shows that the temperature dependent band structure contributes more strongly to the temperature dependence than does Fermi smearing. Figure 5 compares the model with data from a Co/Al 2 O 3 /Co junction by LeClair et al 19 LeClair's MTJs were prepared by ultrahigh vacuum dc/rf magnetron sputtering (Ͻ5ϫ10 Ϫ10 mbar͒ through metal contact masks on Si͑100͒. In situ cleaning in O 2 plasma was used to remove contamination and produce insulation from substrates.…”