Dependence of Pin Surface Roughness for Friction Forces of Ultrathin Perfluoropolyether Lubricant Film on Magnetic Disks by Pin-on-Disk Test

We fabricated supersmooth probes for use in pin-on-disk sliding tests by applying gas cluster ion beam irradiation to glass convex lenses. In the fabrication process, various changes were made to the irradiation conditions; these included one-step irradiation of Ar clusters or two-step irradiation of Ar and N2clusters, with or without Ar cluster-assisted tough carbon deposition prior to N2irradiation, and the application of various ion doses onto the surface. We successfully obtained probes with a centerline averaged surface roughness that ranged widely from 1.08 to 4.30 nm. Using these probes, we measured the friction forces exerted on magnetic disks coated with a molecularly thin lubricant film. Perfluoropolyether lubricant films with different numbers of hydroxyl end groups were compared, and our results indicated that the friction force increases as the surface roughness of the pin decreases and that increases as the number of hydroxyl end groups increases.

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J111022 Changes of Surface Roughness and Surface Energy of Glass Surfaces with Gas Cluster Ion Beam Treatment

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2011._j111022-1 ◽

2011 ◽

Vol 2011 (0) ◽

pp. _J111022-1-_J111022-3

Author(s):

Katsuya NAMBA ◽

Hiroyuki SAKAKIBARA ◽

Hedong ZHANG ◽

Yasunaga MITSUYA ◽

Kenji FUKUZAWA ◽

...

Keyword(s):

Surface Roughness ◽

Surface Energy ◽

Ion Beam ◽

Ion Beam Treatment ◽

Cluster Ion ◽

Gas Cluster Ion Beam ◽

Glass Surfaces

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Adhesion and Friction Behavior of Magnetic Disks With Ultrathin Perfluoropolyether Lubricant Films Having Different End-Groups Measured Using Pin-on-Disk Test

IEEE Transactions on Magnetics ◽

10.1109/tmag.2013.2253451 ◽

2013 ◽

Vol 49 (6) ◽

pp. 2638-2644 ◽

Cited By ~ 16

Author(s):

Hiroshi Tani ◽

Toshiya Mitsutome ◽

Norio Tagawa

Keyword(s):

Friction Behavior ◽

Magnetic Disks ◽

End Groups ◽

Lubricant Films ◽

Perfluoropolyether Lubricant ◽

Pin On Disk ◽

Disk Test

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Roughness Analysis of Episurfaces Grown on Ion-Beam Processed GaSb Substrates

MRS Proceedings ◽

10.1557/proc-829-b6.3 ◽

2004 ◽

Vol 829 ◽

Cited By ~ 1

Author(s):

K. Krishnaswami ◽

D. B. Fenner ◽

S. R. Vangala ◽

C. Santeufemio ◽

M. Grzesik ◽

...

Keyword(s):

Surface Roughness ◽

Statistical Analysis ◽

Ion Beam ◽

Molecular Beam Epitaxial ◽

Power Spectral ◽

Sharp Point ◽

Roughness Analysis ◽

Cluster Ion ◽

Gas Cluster Ion Beam ◽

Substrate Surfaces

ABSTRACTHigh-quality GaSb substrates with minimal surface roughness and thin, uniform oxide layers are critical for developing low-power, epitaxy-based, electronic and optoelectronic devices. Ion-beam processing techniques of gas-cluster ion beam (GCIB) and bromine ion-beam assisted etching (Br-IBAE) were investigated as to their potential for improving the suitability of substrate surfaces for molecular beam epitaxial (MBE) growth. Statistical analysis of the residual surface roughness provides insight into ion-beam processing and its impact on epitaxial growth. Images of episurfaces grown on chemical mechanical polished (CMP), Br-IBAE, and GCIB finished substrates were obtained using atomic force microscopy (AFM) and these were statistically analyzed to characterize their surface roughness properties. Autocorrelation analysis of the first two types of episurfaces showed a quick loss of correlation within ∼100 nm. The episurface with Br-IBAE also showed isotropic mound roughness with sharp point-like protrusions. The GCIB prepared episurfaces exhibited the formation of uniform step-terrace patterns with monatomic steps and wide terraces as indicated by the strong, long range (>0.5 μm) correlations. Statistical analysis of the GCIB episurfaces showed self-similar random fractal behavior over eight orders of magnitude in the power spectral density (PSD) with a fractal dimension of ∼2.5.

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Study of Gas Cluster Ion Beam Planarization for Discrete Track Magnetic Disks

IEEE Transactions on Magnetics ◽

10.1109/tmag.2008.2001618 ◽

2008 ◽

Vol 44 (11) ◽

pp. 3476-3479 ◽

Cited By ~ 10

Author(s):

K. Nagato ◽

H. Tani ◽

Y. Sakane ◽

N. Toyoda ◽

I. Yamada ◽

...

Keyword(s):

Ion Beam ◽

Magnetic Disks ◽

Discrete Track ◽

Cluster Ion ◽

Gas Cluster Ion Beam

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Improvement of surface roughness by ultra-thin film deposition with oxygen cluster ion beam assist deposition

MRS Proceedings ◽

10.1557/proc-749-w17.7 ◽

2002 ◽

Vol 749 ◽

Author(s):

Noriaki Toyoda ◽

Isao Yamada

Keyword(s):

Surface Roughness ◽

Morphological Evolution ◽

Ion Beam ◽

Thin Film Deposition ◽

Film Deposition ◽

Average Roughness ◽

Original Surface ◽

Cluster Ion Beams ◽

Cluster Ion ◽

Gas Cluster Ion Beam

ABSTRACTTa2O5 films were deposited on a rough surface (average roughness 1.3nm, peak-to-valley 14nm) and surface roughness evolutions and improvements by O2 gas cluster ion beam (O2-GCIB) assisted deposition was studied. The average roughness dramatically decreased from 1.3nm to 0.5nm after deposition of Ta2O5 films 20nm in thickness with 7 keV of O2 cluster ion beams. As there was no etching or sputtering of Ta2O5 film by 7keV O2-GCIB irradiations, O2-GCIB assist deposition realized significant improvement of surface roughness by additional deposition of Ta2O5 film whose thickness was close to the peak-to-valley of original surface. It is expected that morphological evolution of the film by GCIB assist deposition becomes completely different from conventional ion assist deposition due to energetic cluster ion impacts.

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Surface Smoothing Effects of Materials Used in Underlayer of MTJ with Gas Cluster Ion Beams

MRS Advances ◽

10.1557/adv.2016.80 ◽

2016 ◽

Vol 1 (5) ◽

pp. 357-362 ◽

Cited By ~ 1

Author(s):

Noriaki Toyoda

Keyword(s):

Surface Roughness ◽

Ion Beam ◽

Random Access ◽

Resistive Random Access Memory ◽

Surface Smoothing ◽

Smoothing Effects ◽

Cluster Ion Beams ◽

Cluster Ion ◽

Materials Used ◽

Gas Cluster Ion Beam

ABSTRACTSurface smoothing of Ru used as underlayer of magnetic tunneling junctions (MTJ) in magneto-resistive random access memory (MRAM) was carried out with gas cluster ion beam (GCIB) in order to improve device characteristics. For Ru films, surface smoothing with 5 kV N2-GCIB irradiation was effective, and CoFe films deposited on smoothed Ru surface also showed smooth surface. From the hysteresis loop measurements of MTJ formed on smoothed Ru with N2-GCIB, it showed improvement of inter-layer coupling magnetic field (Hin) with decreasing the surface roughness of underlayer Ru. It is expected that surface roughness of MgO in MTJ was also improved by smoothing of underlayer Ru with N2-GCIB.

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Nano structure formation by gas cluster ion beam irradiations at oblique incidence

MRS Proceedings ◽

10.1557/proc-849-kk7.9 ◽

2004 ◽

Vol 849 ◽

Cited By ~ 3

Author(s):

Noriaki Toyoda ◽

Isao Yamada

Keyword(s):

Surface Roughness ◽

Oblique Incidence ◽

Incident Angle ◽

Ion Beam ◽

Nano Structure ◽

Sample Rotation ◽

Maximum Value ◽

Cluster Ion ◽

Gas Cluster Ion Beam ◽

Ar Gas

ABSTRACTNano structure formations on Au surfaces by 20 keV Ar gas cluster ion beam (GCIB) irradiation at an oblique incidence were studied. When the incident angle was close to 0° from the surface normal of Au targets, the Au surface was smoothed due to the lateral sputtering effects and there were no structure formations on the surfaces. However, ripples were formed on Au surfaces at incident angle of 60° without sample rotation. When the Au samples were irradiated with Ar-GCIB at 60° with sample rotation, cone like structures with 50nm in diameters were fabricated and the surface roughness had a maximum value. However, the surface roughness suddenly decreased over incident angle of 60°. Even though the surface roughness was the same in the cases with and without sample rotations at 85° incidence, ripple structures were formed parallel to the incoming GCIB directions when there was no rotation. The incident angle dependence of the sputtering depth decreased following cosθ dependence. Very efficient surface smoothing without removing materials were realized with oblique incidence.

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