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Scattering scanning near-field optical microscopy enables optical imaging and characterization of plasmonic devices with nanometer-scale resolution well below the diffraction limit. This technique enables developers to probe and understand the waveguide-coupled plasmonic antenna in as-fabricated heat-assisted magnetic recording heads. In order to validate and predict results and to extract information from experimental measurements that is physically comparable to simulations, a model was developed to translate the simulated electric field into expected near-field measurements using physical parameters specific to scattering scanning near-field optical microscopy physics. The methods used in this paper prove that scattering scanning near-field optical microscopy can be used to determine critical sub-diffraction-limited dimensions of optical field confinement, which is a crucial metrology requirement for the future of nano-optics, semiconductor photonic devices, and biological sensing where the near-field character of light is fundamental to device operation. [ABSTRACT FROM AUTHOR]

The Curie temperature distribution is an important parameter affecting transition noise in heat-assisted magnetic recording. In this paper, we follow up on our recent report on a technique to evaluate the Curie temperature distribution and provide modeling that validates the method as well as provides the experimental bounds for its validity. Thermal modeling is used to determine whether the technique is sensitive to extrinsic sources of grain temperature variations, such as distributions in thermal boundary resistance. The technique is applied to a variety of FePt granular media films of varying alloy composition and chemical ordering, and we find the Curie temperature distribution to depend primarily on grain ordering kinetics. We also present results of grain switching probability as a function of the applied magnetic field and find a non-trivial dependence on the alloy magnetization. [ABSTRACT FROM AUTHOR]

In conventional heat assisted magnetic recording, a thermal write assist is provided by a near field transducer which is constantly energized by a laser during writing. Here, we report experimental and theoretical data where the laser is pulsed, whereby the pulsing can be synchronous or asynchronous to the write clock. It is found that the recording performance of pulsed heat assisted recording is slightly deteriorated when compared with conventional dc operation. This is explained by the combined effect of an increased magnetic-to-thermal offset and fast freezing dynamics. The deterioration of the recording performance can be eliminated by an increase of pulsing frequency so that the inherent low-pass behavior of the thermal response of the medium removes the temperature variations that occur in the recording layer. [ABSTRACT FROM AUTHOR]

Fe-Pt-Ag-SiO2 and Fe-Pt-Ag-C granular recording media with an L10 ordered structure were fabricated using an in-line sputtering system with full-surface alloy targets. To understand the degree of ordering, the x-ray diffraction intensity ratio of a superlattice peak to a fundamental peak was measured for various samples. Some samples showed large intensity ratios despite having low anisotropy energy. This can be explained by the simple theory that the relative intensity at a low diffraction angle increases for samples with weaker preferred orientation. That is, the intensity ratio is affected not only by the degree of ordering but also by the crystalline texture quality. The larger intensity ratio of Fe-Pt-Ag-C media than that of Fe-Pt-Ag-SiO2 media was interpreted as the degraded Fe-Pt(001) texture of Fe-Pt-Ag-C media. Thus, good Fe-Pt(001) texture needs to be achieved without deteriorating the well-isolated granular structure in Fe-Pt-Ag-C media. [ABSTRACT FROM AUTHOR]

The effect of the magnetic and structural properties on recording performance was investigated. Well grain-isolated media were obtained by adding boron and oxygen into the [Co/PD]n multilayer and cooling the substrate. We found that the recorded bit size could be decreased by reducing the magnetic cluster size. Twenty-five-nm bits were successfully recorded on the improved media with a magnetic cluster size of about 30 nm. [ABSTRACT FROM AUTHOR]