For Co and CoNi single layer films, the coercivity is a linear function of the inverse layer thickness and has an angular dependence of a fourfold-like symmetry although only a uniaxial anisotropy exists. For both as-prepared and post field-cooled Co/FeMn bilayers, the exchange field and the coercivity enhancement are proportional to the inverse Co thickness. For as-prepared ones, the exchange ...

anodic aluminum oxide (aao) fabricated by two step anodization technique, is used as a template to synthesize feco nanowire arrays by ac electrodeposition technique. response surface methodology (rsm) is applied to design the experiments, fit an empirical model and optimize the conditions to achieve the best magnetic properties. the magnetic properties, pore dimensions, composition and structur...

We report the temperature and cooling field dependence of the coercivity of exchange biased MnF(2)/Fe bilayers. When the antiferromagnetic surface is in a state of maximum magnetic frustration and the net exchange bias is zero, we observe a strong enhancement of the coercivity, which is proportional to the exchange coupling between the layers. Hence, the coercivity can be tuned in a reproducibl...

We have carried out extensive measurements on novel Fe₃O₄-γ-Fe₂O₃ core-shell nanoparticles of nearly similar core diameter (8 nm) and of various shell thicknesses of 1 nm (sample S1), 3 nm (sample S2), and 5 nm (sample S3). The structure and morphology of the samples were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED)...

Hard/soft permanent magnets have aroused many interests in the past two decades because of their potential in achieving giant energy products as well as their rich variety of magnetic behaviors. Nevertheless, the experimental energy products are much smaller than the theoretical ones due to the much smaller coercivity measured in the experiments. In this paper, the deterioration of the coercivi...

We present an experimental model system that enables quantitative assessment of intergranular exchange coupling in CoCrPt-oxide perpendicular magnetic recording media. A thin film structure consisting of a high coercivity CoPt unicrystal layer and a lower coercivity CoPt layer separated by a thin oxide interlayer is used to model perpendicularly magnetized grains separated by oxide grain bounda...

The underlying mechanism of coercivity in permanent magnets has been a topic of intense interest for many years. It is motivated by the fact that the measured coercivity approaches only 20%–40% of the theoretical nucleation fields as derived from micromagnetic theory. We address this problem by proposing an analytical model, within the framework of the micromagnetic approximation, to examine th...

Structural and magnetic properties of laminated sNd,DydsFe,Co,Nb,Bd5.5 /Fe nanocomposites are investigated. Normally, the addition of the soft phase to the hard phase enhances the remanence but deteriorates the permanent-magnet performance of the material by reducing the coercivity. In the present system, the coercivity increases to 1608 kA/m s20.2 kOed in thermally processed Nd–Dy–Fe–Co–Nb–Bs1...

[1] Goethite (a-FeOOH) is an antiferromagnetic iron oxyhydroxide that forms as a weathering product of iron-bearing minerals. We systematically investigated the lowand room temperature properties of well-defined aluminous goethites [a-(Fe, Al)OOH] with varying grain size and Al content. A marked decrease in the Néel temperature with increasing Al content for goethite lowers the blocking tempera...