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The control of individual magnetic domain walls has potential for future spintronic memory and data processing applications. The speed and reliability of such devices are determined by the dynamic properties of the domain walls. Typically, spin precession limitations lead to Walker breakdown, limiting wall velocity resulting in low mobility. Here, we show the suppression of Walker breakdown by the careful design of small amplitude periodic nanowire structuring to match the periodicity of domain wall spin structure transformations. This opens up a channel for energy dissipation via spin wave emission, allowing a domain wall to maintain its spin structure during propagation. [ABSTRACT FROM AUTHOR]

A detailed investigation of magnetic field alignment of template released ferromagnetic nanowires has been undertaken. The distributions of magnetic field induced angular alignments of Ni0.8Fe0.2, Co, and Ni nanowires grown by electro-deposition and deposited onto substrates from a dilute suspension have been investigated as a function of magnetic field strengths up to ∼1 kOe. The nominal diameter of the nanowires investigated is either ∼200 nm (Ni0.8Fe0.2) or ∼300 nm (Co and Ni). The percentage of nanowires aligned within 0°-10° and 0°-20° of the applied field axis is observed to increase rapidly with increasing field strength up to ∼200 Oe, followed by a slower increase in alignment for the Ni0.8Fe0.2 and Ni wires and little improvement in alignment for the Co wires at higher fields. The proportion of aligned wires within 0°-20° is found to reach ∼82% for Ni0.8Fe0.2, ∼71% for Ni and only 53% for the Co nanowires using a magnetic field of 1 kOe. The influence of wire length upon the efficacy of magnetic alignment is investigated using Ni0.8Fe0.2 and Ni nanowires; this showed that the fractional alignment improved for longer nanowires. [ABSTRACT FROM AUTHOR]

The magnetization reversal processes in ferromagnetic nanowires with sinusoidally modulated edges were investigated as a function of modulation amplitude and wavelength. The reversal processes were studied in two regimes: nucleation controlled reversal and magnetization reversal mediated by domain-wall propagation. In the latter case, domain walls were introduced using both nucleation-pad structures and local pulsed-field injection techniques. The reversal behavior shows that competing effects govern the switching fields in these structures, giving a minimum as a function of modulation wavelength, showing promising results for improved control of domain-wall propagation behavior. The experimental results were interpreted with detailed micromagnetic simulations and an analytical model, based on the demagnetization effects of the modulation upon the spin structure of the wire. The analysis highlights consistent trends in the reversal behavior resulting from modulation, and, significantly, the switching behavior is found to be scalable in relation to the amplitude and wavelength [ABSTRACT FROM AUTHOR]