Abstract:
High-quality and compact arrays of Ni nanowires with a high ratio (up to 700) were
obtained by DC electrochemical deposition into porous anodic alumina membranes with a distance
between pores equal to 105 nm. The nanowire arrays were examined using scanning electron
microscopy, X-ray diffraction analysis and vibration magnetometry at 300 K and 4.2 K. Microscopic
and X-ray diffraction results showed that Ni nanowires are homogeneous, with smooth walls and
mostly single-crystalline materials with a 220-oriented growth direction. The magnetic properties
of the samples (coercivity and squareness) depend more on the length of the nanowires and the
packing factor (the volume fraction of the nanowires in the membrane). It is shown that the dipolar
interaction changes the demagnetizing field during a reversal magnetization of the Ni nanowires,
and the general effective field of magnetostatic uniaxial shape anisotropy. The effect of magnetostatic
interaction between ultra-long nanowires (with an aspect ratio of >500) in samples with a packing
factor of ≥37% leads to a reversal magnetization state, in which a “curling”-type model of nanowire
behavior is realized.
