Laser irradiation effect on carbon overcoat for HAMR application

Ji, Rong; Ma, Yansheng; Shakerzadeh, Maziar; Seet, H.L.; Hu, Jingtian

doi:10.1002/sia.5551

Cited by 7 publications

(14 citation statements)

References 16 publications

(16 reference statements)

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“…Better thermal stability was reported in filtered cathodic vacuum arc (FCVA)-based COCs under laser irradiation in HAMR-like conditions 29 and thermal annealing up to ~940 K 32 , consistent with the good thermal stability, i.e., no change in sp 3 content up to 1100 °C, found in tetrahedral a-C (ta-C) films 33 . However, FCVA-based COCs are not yet used as HDM overcoats due to the presence of macro-particles 6 , 34 .…”

Section: Introductionmentioning

confidence: 64%

“…Reference 28 reported oxidation, degradation, and removal of a ~5 nm hydrogenated amorphous carbon, a-C:H,-based commercial COC on HAMR-compatible HDM in HAMR-like conditions, with 0.25 s total irradiation time. Reference 29 also reported degradation of 4 nm a-C:H-based commercial COC on a FePt-based HDM in HAMR-like conditions, with total heating time ~0.1 ms, corresponding to a 5-year drive life or 157.68 × 10 6 s 29 (see Supplementary Note 1 ).…”

Section: Introductionmentioning

confidence: 99%

“…While HAMR appears to be a solution to all issues, such as small grain size, high magnetic anisotropy, and writability, and paves the way to increasing AD, it raises concerns on the thermal stability of COCs against laser irradiation 28 – 30 . As T C is ~ 700–750 K for FePt 22 , 28 , 29 , reached by laser irradiation, the overcoats for HAMR require thermal stability at least up to ~700–800 K to avoid degradation over time 23 , 28 , 29 .…”

Section: Introductionmentioning

confidence: 99%

“…Efforts are ongoing to test the thermal stability of HDM overcoats, e.g., by using laser 28 , 29 and thermal annealing 30 , and by changing the thermal treatment time 28 , 30 , 31 and heating rate 28 – 31 , to design HAMR-compatible overcoats. Reference 28 reported oxidation, degradation, and removal of a ~5 nm hydrogenated amorphous carbon, a-C:H,-based commercial COC on HAMR-compatible HDM in HAMR-like conditions, with 0.25 s total irradiation time.…”

Section: Introductionmentioning

confidence: 99%

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Graphene overcoats for ultra-high storage density magnetic media

et al. 2021

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Hard disk drives (HDDs) are used as secondary storage in digital electronic devices owing to low cost and large data storage capacity. Due to the exponentially increasing amount of data, there is a need to increase areal storage densities beyond ~1 Tb/in2. This requires the thickness of carbon overcoats (COCs) to be <2 nm. However, friction, wear, corrosion, and thermal stability are critical concerns below 2 nm, limiting current technology, and restricting COC integration with heat assisted magnetic recording technology (HAMR). Here we show that graphene-based overcoats can overcome all these limitations, and achieve two-fold reduction in friction and provide better corrosion and wear resistance than state-of-the-art COCs, while withstanding HAMR conditions. Thus, we expect that graphene overcoats may enable the development of 4–10 Tb/in2 areal density HDDs when employing suitable recording technologies, such as HAMR and HAMR+bit patterned media

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Section: Introductionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Graphene overcoats for ultra-high storage density magnetic media

et al. 2021

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“…Since roughness of these samples is very low to have its influence on contact angle, we negate this factor for contact angle measurement and concentrate on the chemical compositional factor for explaining the results. The commercial COC in sample S-2 is a bilayer overcoat with hydrogenated carbon (CH x ) as a main layer followed by a very thin layer of nitrogenated carbon 57 . On the other hand, FCVA-deposited film is delibretaly grown as a non-hydrogenated and non-nitrogenated carbon (pure carbon layer).…”

Section: Discussionmentioning

confidence: 99%

Ultrathin Carbon with Interspersed Graphene/Fullerene-like Nanostructures: A Durable Protective Overcoat for High Density Magnetic Storage

Dwivedi

Satyanarayana

Yeo

et al. 2015

Sci Rep

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One of the key issues for future hard disk drive technology is to design and develop ultrathin (<2 nm) overcoats with excellent wear- and corrosion protection and high thermal stability. Forming carbon overcoats (COCs) having interspersed nanostructures by the filtered cathodic vacuum arc (FCVA) process can be an effective approach to achieve the desired target. In this work, by employing a novel bi-level surface modification approach using FCVA, the formation of a high sp3 bonded ultrathin (~1.7 nm) amorphous carbon overcoat with interspersed graphene/fullerene-like nanostructures, grown on magnetic hard disk media, is reported. The in-depth spectroscopic and microscopic analyses by high resolution transmission electron microscopy, scanning tunneling microscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy support the observed findings. Despite a reduction of ~37 % in COC thickness, the FCVA-processed thinner COC (~1.7 nm) shows promising functional performance in terms of lower coefficient of friction (~0.25), higher wear resistance, lower surface energy, excellent hydrophobicity and similar/better oxidation corrosion resistance than current commercial COCs of thickness ~2.7 nm. The surface and tribological properties of FCVA-deposited COC was further improved after deposition of lubricant layer.

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