Heat-assisted magnetic recording (HAMR), widely considered to be the next generation technology for high-density data storage devices, uses a tiny plasmonic antenna called a near-field transducer (NFT) to focus light down to a subdiffraction volume. This results in a temporary and local rise in temperature of the recording medium thereby reducing its coercivity, allowing the external magnetic field to write data bits in the medium. The performance of any HAMR system strongly depends on the design of the NFT. The optical performance in terms of the optical coupling efficiency and the spot size for several different NFT designs, including the triangle antenna, E antenna, bowtie aperture, lollipop antenna, and C-aperture, are considered. Also, the corresponding temperature rise in the recording medium and the NFT is calculated and several figures of merit based on the temperature profile are compared for the different designs. This work gives a comparison of the relative performances of different types of NFT and can be a basis for choosing a suitable design for HAMR applications.
Heat-assisted magnetic recording (HAMR) has the potential to keep increasing the areal density in next generation hard disc drives (HDDs) by producing a nanoscale laser spot using optical antenna, called near field transducer (NFT) to locally and temporally heat a sub-diffraction-limited region in the recording medium. The NFTs made of plasmonic nanoscale optical antenna provide the capability of sub-wavelength light focusing at optical frequencies. These antennas are designed using both plasmonic resonance and localized plasmons to produce an enhance field in an area far below the diffraction limit. To reduce the selfheating effect in the NFT, which could cause materials failure that leads to degradation of the overall hard drive performance, the NFT must deliver sufficient power to the recording medium with as small as possible incident laser power. In this paper, the design and characterization of these plasmonic antennas and the effect of optical properties on field localization, absorption, and coupling efficiency will be discussed. Computations of heat dissipation and the induced temperature rise in NFT are carried out to study their dependence on materials’ properties. With the recent significant interests in searching for alternative low-loss plasmonic materials in the visible and near infrared range, the possibility of using alternative plasmonic materials for delivering higher power and simultaneously reducing heating in NFT are investigated.
Microcolumns are widely used for parallel electron-beam lithography because of their compactness and the ability to achieve high spatial resolution. A design of an electrostatic microcolumn for our recent nanoscale photoemission sources is presented. We proposed a compact column structure (as short as several microns in length) for the ease of microcolumn fabrication and lithography operation. We numerically studied the influence of several design parameters on the optical performance such as microcolumn diameter, electrode thickness, beam current, working voltages, and working distance. We also examined the effect of fringing field between adjacent microcolumns during parallel lithography operations. The microcolumns were also fabricated to show the possibility.