Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy

M. Yanagisawa; Masahiro Kunimoto; Takayuki Homma

doi:10.1115/ISPS2016-9513

Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy

M. Yanagisawa, Masahiro Kunimoto, Takayuki Homma

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

2 Citations (Scopus)

Abstract

A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580°C and 366°C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250μs at the heating temperature of 580°C. The result shows no damage can be estimated in DLC films for HAMR because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.

Original language	English
Title of host publication	ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016
Publisher	American Society of Mechanical Engineers
ISBN (Electronic)	9780791849880
DOIs	https://doi.org/10.1115/ISPS2016-9513
Publication status	Published - 2016
Event	ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016 - Santa Clara, United States Duration: 2016 Jun 20 → 2016 Jun 21

Other

Other	ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016
Country	United States
City	Santa Clara
Period	16/6/20 → 16/6/21

ASJC Scopus subject areas

Control and Systems Engineering
Hardware and Architecture
Information Systems

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Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy. / Yanagisawa, M.; Kunimoto, Masahiro ; Homma, Takayuki.

ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016. American Society of Mechanical Engineers, 2016.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Yanagisawa, M, Kunimoto, M & Homma, T 2016, Life estimation of carbon overcoat on magnetic media for heatassisted magnetic recording using novel Raman spectroscopy. in ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016. American Society of Mechanical Engineers, ASME 2016 Conference on Information Storage and Processing Systems, ISPS 2016, Santa Clara, United States, 16/6/20. https://doi.org/10.1115/ISPS2016-9513

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abstract = "A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580°C and 366°C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250μs at the heating temperature of 580°C. The result shows no damage can be estimated in DLC films for HAMR because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.",

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AB - A heat-assisted magnetic recording (HAMR) is expected for a future high density recording of a hard disk drive. However, a carbon overcoat (COC) composed of diamond-like carbon (DLC) or a lubricant film is possibly damaged when a magnetic medium, i.e. CoPt alloy, is heated at around Curie temperature (Tc) of 600K by a near-field HAMR head. We carried out HAMR simulation experiments by using newly developed Raman spectroscopic systems, composed of plasmonic sensors for surface-enhanced Raman scattering (SERS), a pulsed laser heating, and an in-situ temperature measurement with an intensity ratio of anti-Stokes/Stokes lines. It was found that the heated temperature of the COC is higher than that of the magnetic film, i.e., 580°C and 366°C, respectively. Intensity changes of G-band peak in Raman spectra for DLC films were observed during the pulsed laser heating. The Raman intensity was exponentially decreased by oxidation in air, where time constants were calculated as a parameter of a pulse width. Degradation life of the DLC film can be estimated from a critical pulse width, where the time constant is extrapolated to zero. The estimated pulse width for no degradation was 250μs at the heating temperature of 580°C. The result shows no damage can be estimated in DLC films for HAMR because the effective irradiation time is 5ns and the accumulated irradiation time is 0.5ms in HAMR operations.

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