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Porous Fe3O4/Fe/SiO2 core/shell nanorods were fabricated, in which the diameter of the pores was 5–30 nm. The magnetic and electromagnetic properties were investigated. The temperature dependent magnetic measurements showed that these nanorods were ferromagnetic with a Verwey temperature of 129 K. The electromagnetic data indicated that effective complementarities between the dielectric loss and the magnetic loss were realized, suggesting that they have excellent electromagnetic wave absorption properties. Thus the porous core/shell nanorods could be used as a kind of candidate absorber. [ABSTRACT FROM AUTHOR]

Magneto-optical Kerr effect, low-energy electron diffraction, and Auger electron spectroscopy were used to investigate the magnetic properties and the growth mode of ultrathin Co films deposited on 1 ML (monolayer) Ni/Pt(111) at room temperature. No Kerr signal was observed when the thickness of Co film was below 3 ML, and the easy axis of the magnetization was in plane when the thickness of Co was greater than 3 ML at room temperature. The polar Kerr signal appeared after the sample was annealed at 450 K for 1 ML of Co. Further studies in the magnetic properties and surface composition of 3 ML Co/1 ML Ni/Pt(111) during an annealing process showed that the out-of-plane magnetization enhances significantly when Co and Ni atoms diffuse into the Pt substrate. The coercivity of the system can be adjusted by changing the annealing temperature. Measuring at room temperature, the coercivity increases when the annealing temperature rises. The possible mechanism of the evolution of magnetic properties with the structure of the interface is discussed. [ABSTRACT FROM AUTHOR]

With recent developments in heat assisted magnetic recording (HAMR), characterization of HAMR media is becoming very important. We present a multi-functional instrument for testing HAMR media, which integrates HAMR writing, reading, and a micro-magneto-optic Kerr effect (μ-MOKE) testing function. A potential application of the present instrument is to make temperature dependent magnetic property measurement using a pump-probe configuration. In the measurement, the media is heated up by a heating (intense) beam while a testing (weak) beam is overlapped with the heating beam for MOKE measurement. By heating the media with different heating beam power, magnetic measurements by MOKE at different temperatures can be performed. Compared to traditional existing tools such as the vibrating sample magnetometer, the present instrument provides localized and efficient heating at the measurement spot. The integration of HAMR writing and μ-MOKE system can also facilitate a localized full investigation of the magnetic media by potential correlation of HAMR head independent write/read performance to localized magnetic properties. [ABSTRACT FROM AUTHOR]

The intrinsic perpendicular magnetic anisotropy and the domain patterns in granular Co[sub x]Ag[sub 1-x] films with 17%≤x≤62% are studied. Magnetic stripe domains are found in samples with x>=45% and to change to in-plane domain patterns with increasing annealing temperature. This is consistent with the fact that perpendicular magnetic anisotropy becomes negative with annealing. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the effects of doping on the microstructural and magnetic properties of barium ferrite thin films when chromium oxide or yttrium oxide were used as the dopants. Details of the experiment; Results; Discussion and conclusions.

We report on the recording performance of discrete track patterned media fabricated by focused ion beam (FIB). We investigated performance over a small area by spinstand read/write testing. Discrete track patterned regions show smaller magnetic track width and better signal separation between adjacent tracks and therefore higher track density than that of nonpatterned continuous media as a result of reduced side fringe effect and edge noise. We found that, at a designed groove depth of 4-8 nm, the shallow FIB etched grooves already provide good isolation between adjacent tracks, indicating the superiority of ion beam induced modification of magnetic properties in film media over physical modification of disk surface topography. This has implications for discrete track recording and media fabrication. [ABSTRACT FROM AUTHOR]

We have successfully fabricated discrete track media reproducibly using the focused ion beam (FIB). 1 pA and 10 pA FIB beam currents were used effectively for discrete track fabrication; at Ga+ doses of ∼4.2×1016 ions/cm2 and below, media magnetic properties are effectively suppressed, whilst damage to the morphology was minimal. Larger land/groove magnetic contrast was achieved through increasing the ion bombardment rates within this range. Beyond this dosage range, magnetic suppression leveled out, and physical grooves were etched in the media. [ABSTRACT FROM AUTHOR]

Epitaxial films of the full Heusler alloy Co2MnAl were grown on GaAs substrates by molecular-beam epitaxy. The close lattice matching and similar structure to GaAs make this material a good candidate for a spin injector. Magnetization measurements reveal complex ferromagnetic transitions near the Curie point at TC≃800 K. At room temperature, magnetotransport studies show metallic behavior and a giant Hall effect driven by the extraordinary Hall effect. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The motivation for this work is rooted in the reversal process that occurs in perpendicularly magnetic Co/Pd multilayered based bit-patterned media. In our work, temperature effect and angle dependence of critical fields (Hcr) and switching field distribution (SFD) are studied by both experiment and simulation. From our observation, when temperature increases from 77 to 300 K, the critical field of patterned area decreases from 13 to 11 kOe. Absolute SFD decreases from 2.6 to 2.2 kOe as thermal energy assists islands reversal. The relative SFD (SFD/Hcr) keeps constant with temperature. Although critical fields and absolute SFD vary with angles, relative SFD is independent of the field angle. The interactions between islands broaden relative SFD from 12% to 20% after considering dipolar interactions. The relative SFD by simulation agrees well with our experimental observation. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of magnetic properties and high wave-vector magnon excitations in epitaxial Fe(001) films grown on lr(001) substrate. The magnetic properties are investigated by magneto-optical Kerr effect for various thicknesses of Fe him from 4 up to 27 monolayers. The magnon dispersion relation is obtained by means of spin-polarized electron energy loss spectroscopy. By comparing the experimental and theoretical results, we comment on the effect of the strain induced tetragonal distortion in the Fe him and the electronic hybridizations between the him and the substrate on the exchange interaction and magnon dispersion relation. The thickness-dependent measurements show that the magnon dispersion relation does not change signihcantly while changing the him thickness in the regime, where the him is uniformly strained. In addition, the measurements are also performed on thicker Fe Hlms, where the hlms are relaxed into a bulklike structure. The magnon energies close to the zone boundary differ from the ones measured on thick Fe(110) Hlms on W(110). However, the magnon dispersion relation measured for both systems can be well described within the Heisenberg model by using the same effective exchange parameters. [ABSTRACT FROM AUTHOR]