The unidirectional motion of information carriers such as domain walls in magnetic nanostrips is a key feature for many future spintronic applications based on shift registers. This magnetic ratchet effect has so far been achieved in a limited number of complex nanomagnetic structures, for example, by lithographically engineered pinning sites. Here we report on a simple remagnetization ratchet originated in the asymmetric potential from the designed increasing lengths of magnetostatically coupled ferromagnetic segments in FeCo/Cu cylindrical nanowires. The magnetization reversal in neighboring segments propagates sequentially in steps starting from the shorter segments, irrespective of the applied field direction. This natural and efficient ratchet offers alternatives for the design of three-dimensional advanced storage and logic devices.

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The need for flexible and transparent smart materials is leading to substantial advances in principles, material combinations, and technologies. Particularly, the development of optically transparent magnetoelectric (ME) materials will open the range of applications to new directions such as transparent sensors, touch display panels, multifunctional flat panel displays, and optical magnetic coatings. In this work, a flexible and transparent ME composite is made of magnetostrictive Fe72.5Si12.5B15 microwires and piezoelectric poly(vinylidene fluoride‐trifluoroethylene). The high magnetostriction of Fe72.5Si12.5B15 (35 ppm) enables superior ME voltage response (65 mV cm−1 Oe−1) obtained at the critical longitudinal magnetic field equating the transverse anisotropy (14500 A m−1) on the external shell of the microwire.

In this paper we study the effect of magnetostriction of Co-rich amorphous microwire to the noise of the orthogonal fluxgates based on such wires. The magnetostriction was modified by changing the relative amount of iron x with the respect of the total amount of cobalt and iron in the alloy. Specifically we changed x in the composition (Co1−xFex)75Si15B10 casting wires with the following values of x: 0.05, 0.055, 0.06, 0.062, 0.065, 0.07 and 0.08. We found out that the noise indeed depends on the composition of the wire: while it is minimum (2.5 pT/Hz) for x between 0.06 and 0.062 where the magnetostriction is vanishing (λs ≈ 10−7) it significantly increases to tens of pT/Hz for both positive and negative magnetostriction when λs becomes one order of magnitude bigger. We verified that once the composition returns a magnetostriction low enough (around x = 0.06) then the noise does not depend on mechanical stress anymore. In fact the noise of a sensor with x = 0.06 is the identical in its natural curved state and when bended straight; for vanishing magnetostriction the bending does not affect at all the noise, as on the contrary it happens with larger magnetostriction. This suggests that once the wire has composition with x = 0.06 the remaining noise is not caused by mechanical stress. Finally we show how to overcome the problem of offset arising after annealing if continuous annealing current is used. We explain how this could be due by the fact that magnetostriction changes with temperature and even a wire with vanishing magnetostriction at room temperature can became significantly magnetostrictive at annealing temperature. For this reason we propose a method of annealing consisting rising the temperature of the wire while the wire is kept in its natural curved state. In this way no mechanical stress is applied to the wire during the annealing process, when the temperature is high enough to make it magnetostrictive even if it is non-magnetostrictive at room temperature. We show how this method suppresses the offset and significantly reduces the noise.

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