Recent recording areal density and integrated drive performance demonstrations using Heat Assisted Magnetic
Recording (HAMR) suggest that it is a viable technology to succeed conventional magnetic recording. However
challenges still remain for the near field transducer, in particular reliability and sufficient thermal confinement. We
explore a new NFT design, Near field Transducer Gap (NTG), which offers the potential to mitigate some of the issues
in track confinement and thermal profile compared to earlier published studies . The design offers efficiency
improvements, and the potential to reduce unwanted background light and heating that can lead to erasure in the writing
track, and neighbors.
Scaling the areal density, while maintaining a proper balance between media signal-to-noise,
thermal stability and writability will soon require an alternative recording technology. Heat
Assisted Magnetic Recording (HAMR) can achieve this balance by allowing high anisotropy
media to be written by heating the media during the writing process (e.g. by laser light) to
temporarily lower the anisotropy. Three major challenges of designing a HAMR head that tightly
focuses light and collocates it with the magnetic field are discussed: 1) Magnetic Field Delivery,
2)Optical Delivery, and 3) Integration of Magnetic & Optical Field Delivery Components.
Thousands of these HAMR heads were built into sliders and HGAs, and optical and scanning
electron micrograph images are shown. Scanning near-field optical microscopy (SNOM)
characterization of the HAMR head shows that the predicted ~λ/4 full-width half-maximum
(FWHM) spot size can be achieved using 488 nm light (124 nm was achieved). SNOM images
also show that wafer level fabricated apertures were able to effectively eliminate sidelobes from
the focused spot intensity profile. An MFM image of HAMR media shows that Non-HAMR
(laser power off) was not able to write transitions in the HAMR specific media even at very high
write currents, but transitions could be written using HAMR (laser power on), even at lower write
currents. A cross-track profile is shown for a fully integrated HAMR head where the magnetic
pole physical width is ~350 nm, but the written track is ~200nm, which demonstrates HAMR. A
HAMR optimization contour shows that there is an optimum write current and laser power and
that simply going to the highest write current and laser power does not lead to the best recording.
Lastly, some prospects for advancing HAMR are given and a few key problems to be solved are
A spin-polarized dc current can induce steady-state, microwave frequency magnetization dynamics in a nanoscale ferromagnet. The torque that drives these dynamics originates from the exchange of spin angular momentum between conduction electrons and the magnetization. We present measurements of current perpendicular to the plane (CPP) giant magnetoresistance (GMR) nanopillar devices in which this phenomenon occurs. We focus on devices that contain one reference ferromagnetic layer that has a fixed magnetization and one free ferromagnetic layer with a magnetization that responds to spin torque. The resulting spin transfer induced magnetization dynamics combined with GMR lead to resistance noise, which we measure in both the frequency- and time-domain. The appearance of these dynamical states is consistent with spin transfer in that dynamics are observed only for those combinations of current direction and magnetic configuration in which spin torque opposes the FL configuration set by the magnetic field. Furthermore, the amplitude of the resultant resistance noise increases rapidly with increasing current until saturating at a value that is a large fraction of the magnetoresistance between parallel and antiparallel states. This behaviour is contrasted with similar measurements of a current-in-plane (CIP) GMR device in which the magnetic resistance noise is thermally activated.
Heat-assisted magnetic recording (HAMR), also known as hybrid recording, is one of the technologies proposed for extending hard disk drive areal densities beyond a Tb/in<sup>2</sup>. Due to their planar nature and compatibility with existing hard disk drive head fabrication techniques, dielectric optical waveguides have been suggested as a means for delivering light directly to the recording medium or near field optical transducer. In this paper we present spin stand experimental results from a dielectric optical slab waveguide fabricated on an AlTiC slider.
Waveguide electrooptic (EO) beam scanners are of interest for applications requiring high speed, high throughput, low power consumption, and modest deflection. Such devices can be used in high performance optical recording and laser printer heads. We are pursuing a novel waveguide device structure in which prisms are formed by ferroelectric domain inversion in a substrate containing a planar waveguide. The device uses TM optical modes in z-cut substrates and is therefore compatible with waveguides used for high-efficiency optical second harmonic generation (SHG).