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Large spin-transfer effects were observed in spin-valve pillars developed for current-perpendicular-to-plane (CPP) magnetoresistive heads. The investigated samples are complex stacks including laminated free, synthetic/laminated pinned, and nano-oxide layers. The magnetoresistive (MR) transfer curves exhibit current-dependent loop shift and in some particular ranges of current and field, very large noise associated either to stochastic jump of the free layer magnetization or to excitations of steady precessional modes. A very unusual phenomenon of inverted coercivity was observed in the low current range. The spin-transfer effects show an asymmetry as a function of current direction. These experimental results indicate that the spin-transfer effects must be considered in the design of CPP MR heads.

We present an analytical calculation of the shape of the magnetoresistive response of spin-valve structures with synthetic antiferromagnetic pinned layer, i.e., of the form buffer/ferromagnet1/Cu/ferromagnet2/Ru/ferromagnet3/antiferromagnet. The magnetization reversal in the three magnetic layers is assumed to occur via coherent rotation. An analytical expression of the whole hysteresis loop is given as a function of the characteristic parameters of the system (coupling strength through the Ru spacer, ferromagnet3/antiferromagnet pinning energy). We also extended a code based on the Boltzmann equation of transport to calculate the giant magnetoresistance (GMR) amplitude in these structures from the microscopic transport parameters. In order to explain the relatively high GMR amplitude experimentally observed in such spin valves, it is shown that some degree of specular reflection must be introduced at the ferromagnet2/Ru interface. Good agreement with both the shape and amplitude of the experimental magnetoresistance curves can be obtained.

From a phenomenological point of view, we have investigated the effect of scattering at lateral edges on the current-perpendicular-to-plane (CPP) transport properties of submicronic magnetic multilayer pillars. This scattering can be considered as a current-in-plane contribution in the CPP geometry. As a first attempt to calculate the CPP resistance and GMR in this situation, we have combined the serial resistance network model of CPP transport with an exponential variation of the local conductivity as a function of the distance from the edges of the pillars assuming that the scattering is perfectly diffusive at the edges of the pillars. As the lateral size of the pillars decreases below 100 nm, it is shown that this scattering leads to a strong increase in the CPP resistivity as well as a decrease in both ΔR/R and ΔR* area. Furthermore, due to the difference in mean-free paths from layer to layer, the current lines are no longer uniform in the pillar even if the latter is the shape of an infinite cylinder.

By applying a critical bias field instead of conventional surface treatments, the electron emission properties of screen-printed nanotubes were investigated through scanning electron microscopy and emission current-voltage characteristics. After the surface treatment, at the bias field of 2.5V∕μm, the electron emission current density with good uniform emission sites reached the value of 2.13mA∕cm2, which was 400 times higher than that of the untreated sample, and the turn-on voltage decreased markedly from 700to460V. In addition, the enhancement of the alignment of carbon nanotubes to the vertical direction was observed, resulting in an increase in the field-enhancement factor.

The lateral reduction of interconnection in nanoelectronics will require a one-dimensional metallic nanointerconnector. This work presents an achievement of the all-chromium (Cr) nanointerconnection architecture, an approach to nanointerconnection, in which both electrodes and connecting lines are realized by the same Cr using the autocatalytic function of Cr without any additional lithography. Especially observed was the time evolution of the directional lateral growth of Cr nanowires using a dc electric field during the in situ growth of Cr nanowires. Finally, it was confirmed that the in situ-grown Cr nanobridge could act as an electrode interconnector due to its good metallic current-voltage characteristics.

We investigated the effect of specular reflection on the anisotropic magnetoresistance (AMR) of magnetic thin films. The sheet conductance is calculated as a function of the angle between magnetization and current from the microscopic transport parameters by using an extension of the Fuchs–Sondheimer theory. The calculation combines specular reflection on the film interfaces with mean-free paths which depend on the angle between the local magnetization and the electron velocity. The theoretical results are compared with experimental ones. Specular reflection can explain the quite large AMR amplitude observed in thin NiFe films used in the last generation of AMR heads.

This article describes novel array heads for close packed track recording. The heads are batch fabricated on wafers in a linear fashion (Fig. 1). These 60-turn thin-film inductive heads are designed with 6 μm pitch helical coils and planar side-by-side P1/G/P2 yoke structures. The linear head array is placed along the upstream-to-downstream direction of the track. By skewing the array slightly off the track direction, each head of the array aligns to an individual track (Fig. 2). In this case, the track pitch is about 5 μm, which is the yoke height. With this head arrangement, even though thermal expansion causes the head-to-head distance to increase along the upstream–downstream direction, it does not cause a thermally induced track misregistration problem. The increased head-to-head distance only affects the timing of signals between tracks, which can be compensated by the channel electronics. Thus, the thermally induced track misregistration problem is eliminated using this design. The guardbands betwe...

Gradientless propulsion (automotion) of bubbles has been studied on a CaGe ion‐implanted bubble garnet; three different stable S=1 states, as χ±= (1,0,0)± and σ−= (1,2,0)−, were found. The two χ bubbles automote in opposite direction normal to the in‐plane field with χ+ moving along Hi×z; the σ− automote in the same direction as χ+ but at a different pulse bias field margin.(AIP)