Search

The insertion of a nano-oxide-layer (NOL) into a spin valve system is well known to be very effective in enhancing the magnetoresistance ratio at both of current-in-plane (CIP) and current-perpendicular-to-plane (CPP) geometries. Recently, a clear NOL pinning assist effect is reported to be observed in the low temperature range below ~150 K by using the magnetic field cooling method from room temperature (R.T.) in the [Co.sub.0.9] [Fe.sub.0.1] pin-NOL, wherein the NaCl-type CoO-FeO antiferromagnetic component exists. In this paper, the NOL pinning assist effect in a specular spin valve system with (Co-Fe)/Cr pin-NOL is presented. An ultra-thin Cr layer deposit on the Co-Fe layer before oxidation leads to increase the exchange bias field still more with the increment of the blocking temperature (TB) of the (Co--Fe)-NOL biasing in the low temperature range below R.T. and to fully exploit the superior pinning properties of the metallic antiferromagnet (Ir-Mn) at R.T. in the Co-rich region. The effect of ultra-thin Cr layer on the NOL exchange bias is considered from the aspect of the complicated oxide formation and its magnetism. Index Terms--Exchange bias, nano-oxide layer, oxide magnetism, specular reflection.

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)/Fe(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 [degree]C x 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. Index Terms--Exchange coupling, ferromagnetic nanobridge, nano-oxide layer, surface energy.

To understand the mechanism of current-confined-path formation for the current-perpendicular-to-plane type of giant magnetoresistive devices, we have investigated the evolution of an Al monolayer on the Cu (111) surface both by in situ scanning tunneling microscopy and by molecular dynamics simulation. Ultrathin Al nano-clusters were formed on the plateaus and step (or plateau) edges of the Cu surface in the as-deposited state. Upon annealing at 300 [degrees]C, Al atoms migrated toward the step edges by surface diffusion. As a consequence, nanometer-sized Cu channels not covered by Al clusters can be formed. These channels could serve as current-confined paths if subsequent mild Al oxidation is provided. Index Terms--Cu-Al, current-perpendicular-to-plane giant magnetoresistance (CPP-GMR), STM, molecular dynamics.

We have observed high exchange bias for a Cr2O3 film, which was crystallized from an amorphous Cr-oxide by annealing in O2 flow. To clarify the origin of the high exchange bias, we characterized the morphology of the Cr2O3 film. From X-ray diffraction, atomic force microscopy, and transmission electron microscopy measurements, we discovered that our polycrystalline Cr2O3 film was found to grow not to be entirely random orientation, but to form large R-planes on the surface. That is, R-planes were self-organized during crystallization. Since uncompensated Cr spins exist on R-planes of Cr2O3, the origin of the high exchange bias would be the self-organized R-planes. We successfully explained the peculiar temperature-dependent exchange bias and coercivity of the Cr2O3 film. For the Cr2O3 film, perpendicular exchange bias was obtained whereas out of plane direction is hard magnetization axis. This is because of the oblique Cr spin directions from out of plane direction of the film. The results demonstrated that exchange bias higher than coercivity (\mu0Hex\gg \mu0Hc) was realized near room temperature. [ABSTRACT FROM PUBLISHER]

Presents a study that examined the use of current perpendicular to plane giant magnetoresistive (CPP-GMR) heads for magnetic recording. Requirement for CPP-GMR film; Features of developed CPP-GMR films with high performance; Analysis of the head structure optimization for CPP-GMR.

The spin valve films with the insertion of a nano-oxide-layer are expected as nano-constriction SV MR devices such as nano-contact MR. However, the nature of those magnetic coupling, such as the exchange bias and interlayer coupling in SV films with the insertion of a NOL have been not well discussed. In this paper, the interlayer coupling field through Cu spacer and its temperature dependency in SVs with Co1-xFex-NOL and Co1-xFex/Cr-NOL are studied to confirm the influence of the insertion of NOL into SV films. In the case of the SVs with Co0.9Fe0.1-NOL and Co0.9Fe0.1/Cr-NOL, negative interlayercoupling field increases with decreasing temperature in spite of the strength of the Néel coupling of those are almost same with the full metal SV at room temperature. It suggests that the antiferromagnetic interlayer coupling appears by the insertion of NOL into the SVs even though the rough interface. From the result of the temperature dependencies of Hin for each sample, it is considered that the phase of the antiferromagnetic interlayer coupling which related the intensity is varied by the insertion of NOL into the SVs. [ABSTRACT FROM AUTHOR]

To understand the mechanism of current-confined-path formation for the current-perpendicular-to-plane type of giant magnetoresistive devices, we have investigated the evolution of an Al monolayer on the Cu (111) surface both by in situ scanning tunneling microscopy and by molecular dynamics simulation. Ultrathin Al nano-clusters were formed on the plateaus and step (or plateau) edges of the Cu surface in the as-deposited state. Upon annealing at 300 °C, Al atoms migrated toward the step edges by surface diffusion. As a consequence, nanometer-sized Cu channels not covered by Al clusters can be formed. These channels could serve as current-confined paths if subsequent mild Al oxidation is provided. [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.

Presents a study on annealing time and temperature dependences of magnetoresistive (MR) ratio in CoFe/Cu spin-valves. Experimental procedures; Results; Conclusion.