A facile approach for screening isolated nanomagnetic behavior for bit-patterned media

Abstract

Bit-patterned media (BPM) fabricated by the direct deposition of magnetic material onto prepatterned arrays of nanopillars is a promising approach for increasing magnetic recording of areal density. One of the key challenges of this approach is to identify and control the magnetic interaction between the bits (on top of the nanopillars) and the trench material between the pillars. Using independent techniques, including magnetic force microscopy, the variable-angle magneto-optic Kerr effect, and remanence curves, we were able to determine the presence and relative intensities of exchange and dipolar interactions in Co-Pd multilayer-based BPM fabricated by direct deposition. We found that for pitches of 30 nm or less, there were negligible exchange interactions, and the bits were found to be magnetically isolated. As we move to higher densities, the absence of exchange interactions indicates that direct deposition is a promising approach to BPM fabrication.

CoPt/TiN films nanopatterned by RF plasma etching towards dot-patterned magnetic media

“…carried out by annealing after the patterning process. Moreover, the topographical separation necessary to obtain single domain dots is decreasing with the decreasing feature size [40]. This is a promising phenomenon since the feature size of our nanopatterning technique can be decreased to 10-20 nm by decreasing the size of the applied nanospheres.…”

Kinetics of small molecule adsorption studied using precision ellipsometry

“…Thus, our modulator does not contain any magnetic components and is not affected by the magnetic field. Using this modulator, we studied the magnetic properties of cobalt films of thickness down to a nanometre . This success leads naturally to the question: is it only MOKE that can be measured using this modulator?…”

Magnetic interactions in 2D and 3D arrays

“…Different dominating switching mechanisms have been identified for different patterned arrays [Belle et al, 2007;Shaw et al, 2008;Thiyagarajah et al, 2014;Thomson et al, 2006]. In this chapter we show that in addition, identically patterned islands can have a distribution in their reversal mechanism.…”

“…We report a remarkable difference in the angular dependent switching fields among islands and, moreover, a trend from domain wall propagation dominated to nucleation dominated switching from weak to strong islands. Thus far, such differences in switching mechanism have only been found for islands fabricated in different processes [Shaw et al, 2008;Thiyagarajah et al, 2014] or with considerable variations in size Krone et al, 2011]. This effect can be explained qualitatively by a transition from nucleation field to depinning field dominated reversal, in-line with Refs [Delalande et al, 2012;Dittrich et al, 2005;Hu et al, 2005b;.…”

“…The SFD is intrinsic if it is not influenced by the islands environment (e.g. not affected by dipole or exchange interactions [Thiyagarajah et al, 2014]). This is the case if there are large spacings between magnetically well isolated islands.…”