A new technique for heat-assisted magnetic recording media promises improved writeability for next-generation hard drives
Heat-assisted magnetic recording (HAMR) is a new process that realizes the three goals of magnetic recording — readability, writeability and stability. A*STAR researchers have now succeeded in improving its writeability by employing a thermal design that permits a higher density recording1.
A seed-then-heat-sink technique for heat-assisted magnetic recording media promises high signal-to-noise ratios.
HAMR magnetically records data using a laser to locally heat the area being written. Careful control of the thermal spot size on the medium and the thermal gradient during writing allows more information to be written in a smaller area. The recording medium’s thermal profile is influenced by its physical and chemical properties, such as its optical characteristics, microstructure and layer structure, which impact the recording performance and density.
Jiang Feng Hu and his team from the A*STAR Data Storage Institute wanted to better control the thermal profile. The three layers making up the write layer — the heat-sink layer, underlayer and top layer — must support high thermal gradients. In addition, the top layer should be crystalline with controllable microstructural features. An L10-ordered iron–platinum alloy film is a popular top layer as it exhibits a high magnetic anisotropy.
However, choosing a suitable heat-sink layer is challenging. Copper-based materials are attractive due to their high thermal conductivity, but a mismatch between the structures of the crystalline layer and the underlying magnesium oxide limits the growth of the L10 phase.
Although this mismatch can be corrected by inserting a layer between the heat sink and the underlayer, doing so reduces the thermal performance of HAMR media — “This will produce a smaller thermal gradient and media signal-to-noise ratio (SNR),” explains Hu. This is problematic as a high SNR is a critical measure of recording-media performance.
Hu’s team focused on a technical solution called the ‘seed-then-heat-sink approach’ and corresponding media design. As this design does not require an additional layer, it attains a large thermal gradient and a higher media SNR.
A textured copper nitride film is used as a seed layer to induce an orientation of magnesium oxide that promotes L10-ordered iron–platinum film growth. The subsequent deposition of the iron–platinum alloy film, as a high-temperature process, decomposes copper nitrate into copper, which provides a suitable heat-sink layer.
Hu notes this approach enables a large thermal gradient during the writing process. “This large thermal gradient is critical to the iron–platinum-based medium for HAMR application, especially for HAMR media with smaller grains to support the ultrahigh areal density that HAMR technology is targeting,” says Hu.
(1) Hu, J. F., Jian, Z. S., Tie, J. Z., Cher, K. M., Bao, X. X, et al. HAMR medium structure design and its process for excellent thermal performance. IEEE Transactions on Magnetics 50, 3201106 (2014).
One in 5 materials chemistry papers may be wrong, study suggests
15.12.2017 | Georgia Institute of Technology
Scientists channel graphene to understand filtration and ion transport into cells
11.12.2017 | National Institute of Standards and Technology (NIST)
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences