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The behavior of a transverse domain wall (DW) interacting with a ferromagnetic NOT gate is studied with specific emphasis on the role of the DW chirality (sense of rotation of magnetization crossing the DW). We examine both the effect of the incoming DW chirality on the operation of the NOT gate and the effect of the gate on the DW chirality. We find that the chirality of the incoming DW does not affect the range of fields over which the NOT gate operates correctly. The effect of the NOT gate on the DW chirality depends on the chirality of the incoming DW: when the DW is incident on the NOT gate with the wide side of the DW on the inside of the V-shape formed by the gate, the chirality is conserved, but when the DW is incident on the gate with its wide side on the outside of the V-shape, the chirality may reverse. [ABSTRACT FROM AUTHOR]

Time-resolved scanning Kerr microscopy has been used to directly observe magnetostatically coupled transverse domain walls (TDWs) in a pair of closely spaced, curved nanowires (NWs). Kerr images of the precessional response of the magnetic domain to either side of the TDW revealed the TDW as a minimum in the Kerr signal in the region of closest NW separation. When the TDWs were ejected from the NW pair, the minimum in the Kerr signal was no longer observed. By imaging this transition, the static de-coupling field was estimated to be in the range from 38 to 48Oe in good agreement with a simple micromagnetic model. This work provides a novel technique by which DC and microwave assisted decoupling fields of TDWs may be explored in NW pairs of different width, separation, and curvature. [ABSTRACT FROM AUTHOR]

The magnetization reversal of Permalloy (Ni81Fe19) nanowires has been investigated by magneto-optic Kerr effect (MOKE) magnetometry, where one end of the wire exhibits a slope in the thickness. Straight nanowires with a thickness of 7.5 nm, widths of 150 nm, and length of 100 μm were prepared by electron-beam lithography. The sloped ends were achieved by using a penumbra shadow mask during NiFe deposition. The topography of the wires has been studied by atomic force microscopy. One finds that the slope profile can be tuned by the position under the mask, mask-to-sample distance, and angle of deposition. Corresponding MOKE hysteresis loops show a systematic reduction of the coercive field with increasing length of the sloped part. For example, wires where the slope has a length of 45 μm exhibit a coercive field of 11 Oe, whereas nanowires without sloped ends show 107 Oe. [ABSTRACT FROM AUTHOR]

Considerable difficulties exist in generating appreciable magnetic fields, localized on nanometer length scales for future experiments and technologies. Here we experimentally demonstrate selective reversal of a ferromagnetic nanowire by the stray field from a domain wall. The use of a domain wall as a persistent, mobile source of magnetic field is an alternative to localized Oersted fields and current induced switching, with possible use in future domain wall based data storage schemes and magnetic random access memory applications. [ABSTRACT FROM AUTHOR]

Presents a study which demonstrated the growth of thin films of the ferromagnetic semiconductor europium sulphide on (100) oriented gallium arsenide substrates using electron-beam evaporation. Sample preparation; Magnetic and transport properties; Conclusion.

In domain wall (DW) excitation experiments, nonlinearity (NL) intrinsic to the DW dynamics is often hard to distinguish from perturbation due to the confining potential or DW distortion. Here we numerically investigate the dynamic oscillations of magnetostatically coupled DWs: a system well understood in the quasistatic limit. NL is observed, even for a harmonic potential, due to the intrinsic DW motion. This behavior is principally dependent on terms normally associated with the DW canonical momentum and is in contrast with a NL restoring potential. This NL is not observable in quasistatic measurements, relatively insensitive to the confining potential, and may be tuned by the nanowire parameters. The shown NLs are present in any DW restoring potential and must be accounted for when probing DW potential landscapes. [ABSTRACT FROM AUTHOR]

We describe the influence of hard-wall confinement and lateral dimension on the low-temperature transport properties of long diffusive channels and ballistic crosses fabricated in an InSb/In1-xAlxSb heterostructure. Partially diffuse boundary scattering is found to play a crucial role in the electron dynamics of ballistic crosses and substantially enhance the negative bend resistance. Experimental observations are supported by simulations using a classical billiard ball model for which good agreement is found when diffuse boundary scattering is included. [ABSTRACT FROM AUTHOR]

The dynamic injection and propagation of domain walls (DWs) in technologically relevant geometries have been investigated. On short (~10 ns) timescales nucleation of a DW by a localized Oersted field is found to be well described using a Néel-Brown reversal mode. Using locally injected DWs, we test the propagation of DWs over long distances (~100 µm) in close proximity nanowires and beyond the Walker breakdown limit. In nanowires that act as true conduits to a DW, data can be successfully propagated without loss or inter-wire cross-talk. This is in contrast to poorly characterized systems where the DW is found to propagate asynchronously above the critical breakdown field.

Domain wall (DW) pinning in ferromagnetic nanowires is in general a complex process. Distortions of the DW shape make quantitative agreement between modeling and experiment difficult. Here we demonstrate pinning using nanometer scale localized stray fields. This type of interaction gives well-characterized, tailorable potential landscapes that do not appreciably distort the DW. Our experimental results are in excellent quantitative agreement with an Arrhenius-Néel model of depinning--a result only possible when the modeled potential profile agrees fully with that experienced by the DW., (© 2011 American Physical Society)

A sample of 645 volunteer subjects, 50-79 years of age, took part for two consecutive years in a neuropsychological study of perception and memory. The sample was divided into three age groups (50-59, 60-69, and 70-79) in order to examine any age-related changes in performance. On a visual-closure task, similar to that of Gollin (1960), all age groups showed significant improvements in performance (savings) with repeated exposure to the drawings, both after a 15-min, and again after a 1-year, time interval. There were significant differences, however, between the different age groups on all aspects of the task, including number of errors made during initial perceptual performance, percentage of savings over both short- and long-time intervals, and number of items recalled. These findings are contrasted with those from studies of implicit and explicit aspects of verbal memory in normal young and old people, which have found no age-related differences in implicit memory abilities. Implications of these findings, as they relate to the neuropsychological assessment of memory in older people, are discussed briefly.