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In this study, we report the effects of deposition rate and composition of CoFeB on the magnetic properties of CoFeB/MgO/CoFeB structures. We found that the asymmetry exists not only in different deposition stack sequences (bottom structure Ta/CoFeB/MgO and top structure MgO/CoFeB/Ta), but also in different compositions of CoFeB. Co{40}Fe{40}B{20} is more suitable for the bottom structure, while Co{20}Fe{60}B{20} has better perpendicular magnetic anisotropy for the top structure. Based on the results The full pMTJ stacks of structure Ta 5/Co{40}Fe{40}B{20} 1.3/MgO 1/Co{20}Fe{60}B{20}2.2/Top layer (nm unit) were fabricated with different deposition rates and annealing temperatures. We found that low deposition rate (0.03 nm/s) can prevent overlapping magnetization reversal of both free and fixed layer. The antiferromagnetic coupling between the free and fixed layer was found to increase with annealing temperature which can be identified as the consequence of orange-peel coupling. [ABSTRACT FROM AUTHOR]

We investigated gain and fan-out in a current-field driven spin transistor that is driven by a current-induced magnetic field. The basic structure of the transistor consisted of a coplanar waveguide for magnetic field application and an MgO-based magnetic tunnel junction with high magnetoresistance and low resistance area product. Under an assisting ac magnetic field and a dc bias voltage of 0.4 V, we demonstrated substantial power gain of 130, current gain of 4.9, and a fan-out value of 5.7. The scaling of the fan-out value in this device is discussed in detail. The current-field driven spin transistor is proven to be a promising candidate as a basic component of a nonvolatile logic device. [ABSTRACT FROM PUBLISHER]

We have fabricated perpendicular magnetic tunnel junctions consisting of hcp Ru underlayer/hcp CoPt alloy/CoFeB/MgO/CoFeB/CoPt alloy (or Co)/Pt capping layer. By inserting the CoPt alloy (or Co) between the CoFeB and Pt capping layers, it is possible to increase a perpendicular magnetic anisotropy of the top electrode. Using a top electrode of \Co40\Fe40\B20(0.4\ \nm)/\Co72\Pt28(1.6\ \nm)/\Pt, we have obtained an effective magnetic anisotropy of 3.3\times 10^6\ \erg/cm^3 and a tunnel magnetoresistance (TMR) of 9.4%. The analysis of the crystal structure reveals that the low TMR is a consequence of the fcc (111) texture of CoFeB layers. [ABSTRACT FROM PUBLISHER]

This paper reports the results obtained using TbFe and FeCo alloys as the electrodes of MgO-based perpendicular magnetic tunnel junctions (pMTJs). Without annealing treatment, the as-deposited structure showed MgO (001) crystalline texture. The tunnel magnetoresistance (TMR) ratio measured from the patterned cell of size 3\,\times\,6 \mum^2 was 9.5% at room temperature. However, the coercivities of both free and fixed layers were reduced considerably due to the damage caused from the patterning process. The hysteresis loop measurements showed that the magnetic properties of the structures can still be maintained after annealing up to 350 ^\circC. [ABSTRACT FROM AUTHOR]

In this paper, we present experimental results of the ferromagnetic interlayer coupling effect in magnetic tunnel junction devices. This investigation is focused on the sensor size dependency of the ferromagnetic interlayer coupling. The geometry-dependent magnetostatic edge-coupling contribution is estimated by micromagnetic simulation and then subtracted from the net coupling field in order to obtain the correlation between ferromagnetic interlayer coupling and the sensor size. [ABSTRACT FROM AUTHOR]

Thermal stability factor \Delta of the recording layer was studied in perpendicular anisotropy CoFeB/MgO magnetic tunnel junctions (p-MTJs) with various CoFeB recording layer thicknesses and junction sizes. In all series of p-MTJs with different thicknesses, \Delta is virtually independent of the junction sizes of 48–81 nm in diameter. The values of \Delta increase linearly as the recording layer thickness increases. The slope of the linear fit is explained well by a model based on nucleation-type magnetization reversal. [ABSTRACT FROM PUBLISHER]