Stripe and bubble domains in CoCr films

Studies of the domain structure of anisotropic sintered SmCo5 permanent magnets

“…In practice, however, this is not always the case. In some cases, in the images of domain structures with significant perpendicular magnetization component, taken by the conventional Bitter pattern method or the colloid-SEM technique, the domains, and not the domain walls, are marked [25,27,28]. This was also the case for the studied SmCo 5 magnets (cf.…”

“…In Refs. [26,27] the spatial resolution of the colloid-SEM technique was found to be approximately 0.1 mm (note also that this result could be achieved only in the presence of applied low magnetic fields perpendicular to the specimen surface), but it must be remembered that the spatial resolution of this technique is not limited by the resolution of the SEM but mainly by the quality of the colloids and of the specimen surface [26,27]. In the author's opinion, clustering of the colloidal magnetic particles is at present a decisive factor limiting the spatial resolution of the colloid-SEM technique [28].…”

“…In this technique, a thin layer of colloidal suspension of magnetic particles is placed on the specimen surface and after drying the colloid the corresponding magnetic pattern is observed in the SEM [25]. In the absence of external magnetic field, fine magnetic particles are expected to settle on the domain walls, while in sufficiently large external fields (some tens or hundreds of oersteds), they are expected to aggregate to the domains with the same orientation of magnetization as the external field [26,27]. For a review of this technique, see Ref.…”

Neutron reflectometry on Co-Cr layers

“…As thin films of Co-Cr (100-300 nm thick) are candidate materials for perpendicular magnetic recording media, it is important to obtain detailed knowledge of the magnetic properties of such layers. To investigate the microstructure [1] and the magnetic properties [2] of Co-Cr layers several techniques have been used in the past; electron microscopy [3], magnetization measurements and magneto-optics [4], bitter colloid-SEM [5], neutron depolarization [6] and SANS [7]. Neutron depolarization experiments provided evidence that a (thickness-dependent) 'initial layer', with magnetic properties different from those in the domains in the 'bulk' of the film, might exist on the substrate side of the film.…”