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We have investigated the microwave oscillations due to a spin transfer effect induced by direct current in ferromagnetic nanocontact magnetoresistive (NCMR) elements with a current-perpendicular-to-plane spin-valve structure consisting of an FeCo/FeCo–AlOx nano-oxide layer/FeCo multilayer for the reference/spacer/free layers, respectively. Characteristic microwave oscillations were observed in the NCMR elements at different magnetization states induced by the application of a spin-polarized current, which are considered to be related to the introduction of a ferromagnetic NC to spacer layer (large interlayer coupling) and the resonance concerning the stability of the magnetization states of the free and reference layers around the NCs. A marvelously narrow full width at half maximum (FWHM) of l0–20 MHz is observed under a high applied magnetic field where the reference layer magnetization is slightly off axis relative to the pinned direction. By contrast, a wider FWHM of 80–600 MHz is observed at the magnetization state where the magnetization of the free layer just aligned to the antiparallel configuration against the magnetization of the reference layer. These characteristic results are discussed in terms of a spin dynamics mechanism induced by spin transfer torque in the free and reference layers around NCs. [ABSTRACT FROM AUTHOR]

Abstract: To confirm the origin of the exchange coupling through the nano-oxide layer (NOL), the detailed analyses of the magnetization curve and the temperature dependence on magnetization for the Co1-xFex-NOL samples with various oxidation processes are investigated. The field cooling effect is observed for NOL-inserted samples, which suggests the existence of the antiferromagnetic (AFM) component in the NOL. The characteristic temperature (blocking temperature) increases with increase in the Fe content for Co1-xFex(x=0.08,0.17,0.26)-NOL. These results support that NOL pinning appears higher than room temperature. Further, the twisted coupling through the NOL observed for the Co0.50Fe0.50-NOL is discussed from the viewpoint of the magnetic roughness due to the ferrimagnetic nature of the very thin NOL in specular spin valve (SPSV). [Copyright &y& Elsevier]

In this study, we fabricated a Cr2O3 (0001) film without and with a Pt buffer layer and investigated its effect on perpendicular exchange coupling in a Cr2O3/Co3Pt interface. The results showed that the exchange bias field (μ0Hex) and blocking temperature (TB) of a Cr2O3 film without and with Pt were very different. The Cr2O3 film without Pt had a lower μ0Hex of 176 Oe and a lower TB of 75 K, whereas that with Pt had a higher μ0Hex of 436 Oe and a higher TB of 150 K. We discussed this difference in μ0Hex and TB values based on collinear/non-collinear coupling in a ferromagnetic and antiferromagnetic interface using Meiklejohn and Bean's exchange anisotropy model. [ABSTRACT FROM AUTHOR]

When the surface energy of bottom layer is lower than top layer, the atoms of bottom layer should be pumped up at the triple point of the grain boundary. This phenomenon should be useful for the fabrication of well-defined nanobridge. To confirm the Atom Pumping-Up mechanism for metal/metal thin films, Ta(2 nm) on epitaxial MgO(001)IFe(001) films were prepared by the electron beam deposition method. The Pumping-Up mechanism was successfully confirmed by the Auger Electron Spectroscopy, the in situ Scanning Tunneling Microscopy, and the Transmission Electron Microscope observation after heat treatment of 400 ° C × 30 min. The size of the Fe bridges was 2-5 nm. Furthermore, the magnetic exchange coupling effect on the magnetization process through the ferromagnetic bridges between two Fe layers in MgO/Fe/Ta/Fe after Atom Pumping-Up shows a good agreement to the micromagnetics simulation result from the assumption of ferromagnetic bridges with the size of 1-4 nm. [ABSTRACT FROM AUTHOR]

The bulk and interface spin scattering asymmetric coefficients, βF and γF/N, respectively, as well as the interfacial specific resistance, AR*F/N, contribute to the total resistance change-area product, ΔRA, in current-perpendicular-to-plane (CPP) geometry. In this paper, we report the effect of the insertion of a 1 nm Fe layer into ferromagnetic (F)/non-ferromagnetic (N) interfaces on the spin dependent transport properties. Using the Valet-Fert theory based on the two-current model in which ΔRA is obtained as a function of thicknesses of the ferromagnetic layer (3, 4, and 5 nm), we experimentally deduced the values of βF, γF/N, and AR*F/N of exchange-biased spin valves (EBSVs) for an artificially ordered B2 state Fe50Co50 alloy as a magnetic layer and an Ag spacer layer. [ABSTRACT FROM AUTHOR]

Presents a quantitative study of the ferromagnetic interlayer coupling of the Nano-Oxide Layers. Magnetoresistive ration of spin-valves; Details on the experiment; Results and conclusion.