Heat-assisted magnetic recording (HAMR) is being developed as the next-generation magnetic recording technology. Critical aspects of this technology, such as plasmonic near-field transducer (NFT) and high anisotropy granular FePt media, have been demonstrated and reported. However, progress with areal density was limited until recently. In this paper, we report a basic technology demonstration (BTD) of HAMR, at 1.007 Tbpsi with a linear density of 1975 kBPI and track density of 510 kTPI, resulting from advances in magnetic recording heads with NFT and FePtX media. This demonstration not only shows significant areal density improvement over previously reported HAMR demos, more significantly, it shows HAMR recording at a much higher linear density compared to previous reports. It is an important milestone for the development of such a new technology. Many challenges still remain to bring this technology to market, such as system reliability and further advancement of areal density.

HAMR Areal Density Demonstration of 1+ Tbpsi on Spinstand

In this paper, we report a micromagnetic modeling study on the recording processes in heat-assisted magnetic recording. By solving coupled Landau-Lifshitz-Bloch equations, recording simulations are performed for granular FePt-L10 thin film media. The calculated signal-to-noise ratio shows strong dependence on recording field amplitude, especially for media of small size grains. It is found that low field amplitude yields unsaturated recording whereas high field amplitude causes transitions to be broadened immediately after writing. High thermal gradient will alleviate the transition broadening, allowing high field amplitude to be employed so that completed magnetization in the recorded bits can be achieved in small grin size media. The study concludes that the ability in obtaining the expected signal-to-noise ratio performance at very small grain pitches would critically rely on whether sufficiently high thermal gradient can be achieved in the media.

Understanding Signal and Noise in Heat Assisted Magnetic Recording

The objective is to familiarize students with steady and unsteady heat transfer by conduction and with the effect of thermal conductivity upon temperature distribution through a homogeneous substance. The elementary heat conduction experiment presented is designed for associate degree technology students in a simple manner to enhance their intuition and to clarify many confusing concepts such as temperature, thermal energy, thermal conductivity, heat, transient and steady flows. The equipment set is safe, small, portable (10 kg) and relatively cheap (about $1200): the electric hot plate 2 kg (4.4 lb) for $175: the 24 channel selector and Thermocouple Digital Readout (Trendicator) 4.5 kg (10 lb) for about $1000; the three metal specimens (each of 2.5 cm diameter and 11 cm length), base plate and the bucket all about 3 kg (7 lb) for about $25. The experiment may take from 60 to 70 minutes. Although the hot plate surface temperature could be set from 90 to 370 C (maximum of 750 watts) it is a good practice to work with temperatures of 180 to 200 C (about 400 watts). They may experiment in squads of 2, 3 or even 4, or the instructor may demonstrate it for the whole class.

/pdf/thermal-conductivity-of-metals-3mw1omos6j.pdf

Thermal conductivity of metals

Increasing the density of data storage is crucial to the future of inexpensive digital technology. The large majority of storage in the “Cloud” consists of magnetic hard-disk drives. The continued evolution of this USD$30 billion industry depends on the commercial introduction of heat-assisted magnetic recording (HAMR). This technology uses heat from a laser beam confined well below the diffraction limit, <50-nm wide, to write to media near 450°C with high magnetic anisotropy that would normally be unwriteable under available magnetic fields. This high anisotropy guarantees thermal stability even for grain sizes around 5-nm diameter, which are necessary for major increases in storage density. In this article and in the articles in this issue, we introduce HAMR requirements and discuss its numerous interdisciplinary materials challenges, including high-temperature/efficient plasmonic materials, low-loss optical materials, highly ordered/thermally anisotropic nanoscale magnetic grains, block copolymers for directed assembly below 10 nm, high-temperature nanometer-thick coatings/lubricants, materials/interfaces to control heat flow at nanometer length scales, and advanced spintronic materials.

/pdf/materials-for-heat-assisted-magnetic-recording-1ajozi4qul.pdf

Materials for heat-assisted magnetic recording

This thesis describes research done at Philips Research on near-field optical data storage systems with a solid immersion lens.

Near field optical data storage

Heat-assisted magnetic recording (HAMR) is being developed as the next-generation magnetic recording technology. High anisotropy granular media such as FePt-C have been demonstrated as HAMR media for ∼2 Tbpsi (terabits per in2) recording density. In order for this technology to reach its full potential of 4–5 Tbpsi, more progress and innovations are needed for the key requirements for HAMR media, including microstructure, design, magnetic distribution, and thermal design. Beyond granular media, heated-dot magnetic recording (HDMR) is planned to extend areal density toward 10 Tbpsi. HDMR combines similar advanced recording layer materials with advanced patterning techniques to fabricate <10-nm rectangular dot media.

Heat-assisted magnetic recording media materials

For vapor deposited FePt to be realized as a magnetic recording medium, a basic understanding of the fundamental materials processes in chemical ordering and their interactions with sputter deposition is required. For such applications, a magnetically decoupled nanostructure is necessary as used for longitudinal and perpendicular schemes. The elevated temperatures required for FePt chemical ordering is a major paradigm shift from conventional fabrication. With an understanding of the role of individual materials processes involved with chemical ordering, their implications on physical vapor deposition or other manufacturing systems can be addressed. The feasibility of such processing is shown here with examples of FePt carbon and FeCuPt SiO deposited at elevated temperature.

Materials Processing for High Anisotropy Granular Media

Heat-assisted magnetic recording is a promising approach for enabling large increases in the storage density of hard disk drives. A laser is used to momentarily heat the recording area of the medium to reduce its coercivity below that of the applied magnetic field from the recording head. In such a system, the recording materials have a very high magnetic anisotropy, which is essential for the thermal stability of the magnetization of the extremely small grains in the medium. This technology involves new recording physics, new approaches to near field optics, a recording head that integrates optics and magnetics, new recording materials, lubricants that can withstand extremely high temperatures, and new approaches to the recording channel design. This paper surveys the challenges for this technology and the progress that has been made in addressing them.

Heat Assisted Magnetic Recording This technology uses temporary laser heating to increase hard drive storage density; modeling indicates the potential to exceed the capability of perpendicular recording by an order of magnitude.

An apparatus comprises a magnet housing dimensioned to receive a heat-assisted magnetic recording (HAMR) medium or a hard disk drive comprising at least one HAMR medium. A degausser is disposed in the magnet housing and is configured to generate at least one field sufficient to erase the HAMR medium, where the HAMR medium has a coercivity of between about 20 and 100 kOe at room temperature.

Method and apparatus for degaussing heat-assisted magnetic recording media

This paper discusses heat-assisted magnetic recording (HAMR) media requirements and challenges for areal densities (AD) beyond 1 Tb/in2. Based on recent roadmap discussions the focus is primarily on granular chemically ordered L10 FePtX-Y-perpendicular media with reduced average grain size down to 〈D〉 = 3-5 nm relative to current CoCrPt based perpendicular magnetic recording (PMR) media with average grain size 〈D〉 = 7-9 nm. In HAMR media the combination of thermal conductivity and Curie temperature TC determines the required laser power during recording. Key challenges are sigma variations of D and TC which need to be reduced to σD/D ~ 10-15% and σTC/TC ~ 2%. In addition AD is limited by switching field distribution (SFD) and thermal spot size. The key goal going forward is to optimize heads, media, head-media-spacing (HMS) and read-back channel technologies to extend AD to 4 Tb/in2 and beyond.

A HAMR Media Technology Roadmap to an Areal Density of 4 Tb/in $^2$ </formula

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