Narrow Results

A series of NiO-containing Co/Cu/Co spin valves with the thickness Co of 5 nm and Cu of 2 nm were fabricated by magnetron sputtering technique with different growth parameters. NiO layer with the thickness of 40 nm is used as a coupling layer. Magnetoresistance (MR) of the spin valve with NiO layer under the bottom of Co/Cu/Co (BSV) is larger than that of the spin valve with NiO layer at the top of Co/Cu/Co (TSV) at room temperature. The MR values can be improved with decreasing the sputtering rate of copper layer. The studies by in-situ grazing incident X-ray scattering on the annealing temperature dependence of MR show that the decrease of the interface roughness between Co and NiO may increase the MR value, while the decrease of the coupling effect between NiO and Co decreases the MR value.

Top and bottom NiO-pinning spin valves, e.g. Ta/NiO/Co/Cu/Co/Ta and Ta/Co/Cu/Co/NiO/Ta multilayers, were investigated extensively. At the same thickness of the Cu layer, the GMR ratio for the bottom one is about 30% larger than that for the top one, which is unambiguously due to the roughness effect at the NiO/Co interface. The roughness of NiO/Co interface of the top NiO-pinning spin valve is much larger than that of the bottom one, which may be due to the deposition sequence. On the other hand, although the preferred orientation of the top NiO-pinning spin valve is more prominent than that of the bottom one, it seems not favorable to the specular reflection effect.

In this paper, crystal and magnetic properties of proton irradiated giant magnetoresistance spin valves (GMR-SVs) were investigated based on Ta/NiFe/CoFe/Cu/CoFe/IrMn/Ta stack. GMR-SVs were fabricated by magnetron sputtering and irradiated by 5 MeV proton energy. After irradiation, the magnetic phase of GMR-SV core structures was not affected distinctly while the crystal structure of Ta changed with the radiation dose and dose rate. Degradation of the saturated magnetization and the magnetoresistance ratio was shown in the proton-irradiated samples from the magnetization hysteresis curves and the magnetoresistance measurements, which was explained from the change in the zero-field resistance and the exchange interaction.

This paper reviews the current status of maximizing output power in spin transfer nano-oscillators (STNOs). The key factors affecting output power and the methods to maximize output power in STNOs are briefly introduced. The recent development trends for STNOs are also reviewed in this paper. This article is one of a series devoted to the subject of Latest Progress on Spintronics Devices.

The dependence of the free layer coercivity on the applied magnetic field (MF) deviation from the main anisotropy directions (free layer easy axis (EA) and pinning direction (PD)) and on 〈111〉 texture strength have been studied on [Ta, (Ni₈₀Fe₂₀)₆₀Cr₄₀]/Ni₈₀Fe₂₀/Co₉₀Fe₁₀/Cu/Co₉₀Fe₁₀/Mn₇₅Ir₂₅/Ta spin valves. The effect of interlayer coupling, magnetic anisotropy and texture on the spin valve coercivity is analyzed. Technological steps aimed at the low field coercivity reduction down to few tenths Oersted have been received.

Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.