Observation of recorded magnetization pattern by electron holography

Abstract

Electron holography was employed for experiments involving a high-density magnetic recording, in which it was possible to directly observe streams of magnetic flux. The magnetic flux distribution in recorded films, and the maximum packing density in high-coercivity evaporated cobalt film were investigated. With magnetic longitudinal recording the resultant highest density was 170 000 bits per inch. This experiment has proven that electron holography is useful for the study of magnetic recording.

Interpretable and Efficient Interferometric Contrast in Scanning Transmission Electron Microscopy with a Diffraction-Grating Beam Splitter

“…Off-axis electron holography offers a more interpretable measurement of phase with respect to a vacuum reference wave. This allows, for example, imaging of magnetic bits in recording media [20] and insight into the charge distribution and asymmetry of nanoparticles [21]. However, as interference fringes are in real space, resolution is limited by the spacing of fringes [22], coherence, and biprism stability.…”

Determination of the surface morphology of gold-decahedra nanoparticles using an off-axis electron holography dual-lens imaging system

“…In our case we chose a field of view (FOV) between 250 and 300 nm. Other FOVs can be chosen just as easily and reproducible for the characterization of materials in nanotechnology for extracting quantitative information such as electrostatic fields (Ortolani et al, 2011; Zhang et al, 1992; McCartney et al, 1997, 2010), magnetic fields (Hirayama et al, 1995; Osakabe et al, 1983), non-stained biological samples (Simon et al, 2004, 2008), and impurities in solids, determination of the thickness and the lattice distortion in nanostructured materials and dopant profiles and strain measurement in semiconductor technology (Cooper et al, 2011; Muehle et al, 2005; Hytch et al, 2011). …”

Off‐axis electron holography of magnetic nanowires and chains, rings, and planar arrays of magnetic nanoparticles

“…Earlier applications of electron holography to the characterization of magnetic structures and continuous films are not described. The reader is instead referred to previous studies describing the characterization of fine particles (Tonomura et al, 1980), recording media (Osakabe et al, 1983), the Aharonov-Bohm effect (Tonomura et al, 1986), superconducting vortices (Bonevich et al, 1993), hard magnets (McCartney and Zhu, 1998), patterned elements (Dunin-Borkowski et al, 2000), magnetotactic bacteria (Dunin-Borkowski et al, 2001), and charge order in manganites (Loudon et al, 2002).…”