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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.

We report visualizations of the bidirectional near-field optical transfer function for a waveguide-coupled plasmonic transducer as a metrology technique essential for successful development for mass-fabricated near-field devices. Plasmonic devices have revolutionized the observation of nanoscale phenomena, enabling optical excitation and readout from nanoscale regions of fabricated devices instead of as limited by optical diffraction. Visualizations of the plasmonic transducer modes were acquired both by local near-field excitation of the antenna on the front facet of a waveguide using the focused electron beam of a scanning electron microscope as a probe of the near-field cathodoluminescence during far-field collection from the back facet of the waveguide, and by local mapping of the optical near-field for the same antenna design using scattering scanning near-field optical microscopy as a probe of the near-field optical mode density for far-field light focused into the back facet of the waveguide. Strong agreement between both measurement types and numerical modeling was observed, indicating that the method enables crucial metrological comparisons of as fabricated device performance to as-modeled device expectations for heat-assisted magnetic recording heads, which can be extended to successful development of future near-field-on-chip devices such as optical processor interconnects.

In the twenty-first century, scanning probe microscopy characterization techniques have seen significant progress and are capable of probing complex structures and devices for a variety of near-surface features and phenomena with nanometer scale resolution. With modest customization, we can deploy these techniques for industrial metrology purposes in a simultaneous and multimethod system capable of shedding light on device function and failure modes, as well as determining the most efficient methods for data collection. To demonstrate this concept with a current, complex industrial device under development, several scanning probe microscopy techniques advantageous to the progress of heat-assisted magnetic recording heads were selected. This work describes simultaneous and multimethod approaches for performing heat-assisted magnetic recording head characterization using atomic force microscopy with scattering scanning near-field optical microscopy simultaneously performed with magnetic force microscopy or photo-induced force microscopy that could be extended to applications of other complex nanoscale devices. We demonstrate that the optical and magnetic fields are overlapping for fabricated heads, which is necessary for performing heat-assisted magnetic recording. We also observed that the multimethod atomic force microscopy methods show strong agreement between the measured optical and magnetic fields and the locale of their associated parts on the head. [ABSTRACT FROM AUTHOR]

Plasmonic devices, made of apertures or antennas, have played significant roles in advancing the fields of optics and opto-electronics by offering subwavelength manipulation of light in the visible and near infrared frequencies. The development of heat-assisted magnetic recording (HAMR) opens up a new application of plasmonic nanostructures, where they act as near field transducers (NFTs) to locally and temporally heat a sub-diffraction-limited region in the recording medium above its Curie temperature to reduce the magnetic coercivity. This allows use of very small grain volume in the medium while still maintaining data thermal stability, and increasing storage density in the next generation hard disk drives (HDDs). In this paper, we review different plasmonic NFT designs that are promising to be applied in HAMR. We focus on the mechanisms contributing to the coupling and confinement of optical energy. We also illustrate the self-heating issue in NFT materials associated with the generation of a confined optical spot, which could result in degradation of performance and failure of components. The possibility of using alternative plasmonic materials will be discussed.

We have nanofabricated patterns of holes, pits, slits, and ridges in silver and gold films on quartz substrates by focused ion beam (FIB) and studied the optical properties of these resonant structures as a function of metal type, wavelength, pattern dimensions, feature dimensions, and film thickness. We find enhanced transmission due to both surface plasmon resonances and theoretically predicted waveguide resonances. The enhancement effect extends to a hole size as small as 35 nm. We also find that 35-nm-wide resonant slits can have transmission normalized to area that is 10 000 times larger than through a simple circular aperture of the same dimension. Plasmon enhanced transmission was also found for compact structures composed of only one raised feature on each side of the aperture. These structures show promise for applications in thermally assisted recording (TAR). Index Terms--Magnetooptic recording, near-field, superparamagnetic limit, surface plasmon, thermomagnetic recording.

Micromechanical cantilevers are commonly used for detection of small forces in microelectromechanical sensors (e.g., accelerometers) and in scientific instruments (e.g., atomic force microscopes). A fundamental limit to the detection of small forces is imposed by thermomechanical noise, the mechanical analog of Johnson noise, which is governed by dissipation of mechanical energy. This paper reports on measurements of the mechanical quality factor Q for arrays of silicon-nitride, polysilicon, and single-crystal silicon cantilevers. By studying the dependence of Q on cantilever material, geometry, and surface treatments, significant insight into dissipation mechanisms has been obtained. For submicron-thick cantilevers, Q is found to decrease with decreasing cantilever thickness, indicating surface loss mechanisms. For single-crystal silicon cantilevers, significant increase in room temperature Q is obtained after 700 [degrees] C heat treatment in either [N.sub.2] or forming gas. At low temperatures, silicon cantilevers exhibit a minimum in Q at approximately 135K, possibly due to a surface-related relaxation process. Thermoelastic dissipation is not a factor for submicron-thick cantilevers, but is shown to be significant for silicon-nitride cantilevers as thin as 2.3/ [micro]m. [434] Index Terms--Cantilever, force sensor, mechanical dissipation, micromechanical resonator, quality factor, surface losses.

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]

Plasmonic devices are capable of efficiently confining and enhancing optical fields, serving as a bridge between the realm of diffraction-limited optics and the nanoscale. Specifically, a plasmonic device can be used to locally heat a recording medium for data storage. Ideally, the recording medium would consist of individually addressable and non-interacting entities, a configuration that has been regarded as the ultimate future hard-drive technology. Here, we describe a plasmonic nano-antenna that is fully integrated into a magnetic recording head and its use for thermally assisted magnetic recording on both continuous and fully-ordered patterned media using nanosecond pulses in a static tester configuration. In the case of patterned media at 1.5 Pb m−2 (∼1 Tb inch−2) with 24-nm track pitch, we show ideally written bits without disturbing neighbouring tracks. We find a dramatic improvement in track width and optical efficiency compared to continuous media and show that this is largely due to advantageous near-field optical effects. [ABSTRACT FROM AUTHOR]