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This paper reports on the integration of magnetic tunnel junction (MTJ) sensing devices with magnetoresistance responses above 150% on flexible substrates. The sensors are integrated in a fabrication process based on polyimide materials, and demonstrate sensitivities up to 250~\mu \textV /Oe for bias currents in the 100- \mu \textA range. Assessment of the sensors performance is done under controlled mechanical load conditions, and the magnetoresistance is only slightly affected (1% variation) while sensitivity changes by 7.5% when the bending radii reduce down to 5 mm. The results demonstrate the high potential of the MTJ sensors to be used in applications requiring bending and conforming to non-planar geometries, bringing magnetoelectronic technologies to hard-to-reach regions of space. [ABSTRACT FROM PUBLISHER]

We investigated the tunneling magnetoresistance (TMR) properties for the magnetic sensor application in MgO-based magnetic tunnel junctions (MTJs) using a perpendicularly magnetized [Co/Pd]-based reference layer and an in-plane magnetized CoFeB sensing layer with various thicknesses ( $t_{{\mathrm{CoFeB}}}$ ). Linear TMR curves to an out-of-plane magnetic field were successfully obtained with a dynamic range of more than 600 Oe, corresponding to the coercivity of the [Co/Pd]-based reference layer. The MTJs showed the highest sensitivity of 0.026%/Oe for $t_{{\mathrm{CoFeB}}} = 1.8 nm and the smallest nonlinearity of 0.11% full scale for t\mathrm{CoFeB} = 3 nm. We clarified that the sensitivity and the nonlinearity in the MTJs are significantly associated with t{\mathrm{CoFeB}} , which is attributed to the change in the anisotropy field of the CoFeB sensing layer. [ABSTRACT FROM PUBLISHER]

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]

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]

Scanning tunneling microscopy (STM) is used to study transport in magnetic double tunnel junctions (DTJs) formed using a fixed transparency barrier of a patterned tunnel junction (TJ), and a variable tunnel barrier between the top electrode of the patterned junction and the STM tip. A sufficiently thin top electrode has been predicted to result in a rectification of charge current through a DTJ when the two barriers have different transparency. Our measurements indeed show a high current rectification ratio for 3-nm-thick, continuous film top electrodes, which is observed for junctions with asymmetric tunnel barriers. [ABSTRACT FROM AUTHOR]