ITE Technical Report
Online ISSN : 2424-1970
Print ISSN : 1342-6893
ISSN-L : 1342-6893
24.67
Showing 1-18 articles out of 18 articles from the selected issue
  • Type: Cover
    Pages Cover1-
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Type: Index
    Pages Toc1-
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Kazuhiro OUCHI
    Type: Article
    Session ID: MMS2000-22
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    In harmony with a dramatic advancement in information technology, although basic concept in perpendicular recording has never changed, new progresses have been achieved to surpass some physical limitations for answering severe technolgical demands of future high density storage. Genuine perpendicular recording with a double layer medium with a soft magneteic layer has become in the main current of developments. Challenges to a high recording resolution, reduction of mesium noise, and theremal stability have been performed. To overcome the thermal instability in the future Tera bites class density, new candidates media of Co/Pd artifitial lattice and FePt have been also proposed. Finally, the recently achieved recording performances by using advanced Co-Cr-M media are described.
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  • J.P. Wang, Yingfan Xu, Zhengsheng Shan, Tow Chong Chong
    Type: Article
    Session ID: MMS2000-23
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Granular hcp-(CoCrPt)_<100-X>C_X and (CoCrPt)_<100-X>(SiO_2)_X thin films have been fabricated by sputtering multilayers followed by post-deposition annealing. Magnetic and structural properties of the films have been investigated in detail. The CoCrPt-C granular film with the high coercivity of 4.4 kOe and film anisotropy of 3.6x10^6 erg/cm^3 and CoCrPt-SiO_2 granular film with high coercivity of 5.6 kOe and film anisotropy of 4.3x10^6 erg/cm^3 have been achieved. Grain isolation in magnetic layer was improved by the segregated SiO_2 or C in grain boundaries and further enhanced by post-deposition annealing. These granular films possess well in-plane preferred orientation of magnetic moment, which is desirable for longitudinal recording.
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  • Masaaki Futamoto, Yoshiyuki Hirayama, Nobuyuki Inaba, Yukio Honda, Ats ...
    Type: Article
    Session ID: MMS2000-24
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Microstructures of CoCr-alloy thin film media were investigated by cross-sectional transmission electron microscopy focussing on the initial growth region of the magnetic layer grown on nonmagnetic underlayers. An introduction of nonmagnetic hcp-CoCrRu layer between an hcp-CoCrPt recording layer and an hcp- or a bcc-underlayer improved the crystallographic quality of the initial growth region. Coercivity and squareness of thin film media increased by realizing good hetero-epitaxy between the nonmagnetic and the magnetic hcp-layers.
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  • Dongping WU, Fulin WEI, Zheng YANG, Mitsunori MATSUMOTO
    Type: Article
    Session ID: MMS2000-25
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    The effects of substrate temperature (Ts), oxygen partial pressure and target composition on structure and magnetic properties of the sputtered strontium ferrite films were investigated. It is found that when Ts>400℃ the films begin to crystallization and the increase of substrate temperature and oxygen partial pressure are beneficial to improve c-axis orientation normal to the film plane. The saturation magnetization Ms increases with the increase of substrate temperature Ts and decreases slightly with the increase of oxygen partial pressure. The film prepared by the target composition of SrO・4Fe_2O_3 in 600℃ has highest value of Ms and Hc in perpendicular direction, that is 321 emu/cm^3 and 3.4 kOe, respectively.
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  • Setsuo YAMAMOTO, Kei HIRATA, Hiroki KURISU, Mitsuru MATSUURA, Takanori ...
    Type: Article
    Session ID: MMS2000-26
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Using reactive sputtering without post-oxidization process, high coercivity ferrite thin-films with perpendicular magnetic anisotropy were prepared without NiO underlayer. The ferrite thin-film deposited on glass substrate have smooth surface and are composed of small grains. Perpendicular recording was performed on the ferrite thin-film hard disk. The ferrite thin-films with high coercivity are successfully prepared on flexible film substrates (Polyimide and PET).
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  • S. Nakagawa, N. Funabashi, J. Feng, M. Naoe
    Type: Article
    Session ID: MMS2000-27
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    M-type Ba ferrite (BaM) disks were prepared on Pt and Pt-Ta underlayers using facing targets sputtering apparatus. Pt underlayers are more stable and more effective than ZnO underlayers to promote the c-axis orientation of BaM layers deposited on them, especially for extremely thin BaM films. Pt-Ta underlayer was used to decrease the grain size of BaM layers deposited on them. BaM/Pt-Ta disks revealed larger S/N ratio than BaM/Pt disks because of their larger signal output and lower media noise level. BaM disks with 50 nm thick BaM layers revealed lower noise level and larger S/N ratio than that with 100 nm thick BaM layers due to smaller grain size.
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  • S.N. Piramanayagam, J.P. Wang, Z.S. Shan, Weichun Ye, Tow Chong Chong
    Type: Article
    Session ID: MMS2000-28
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    A novel method to determine dynamic remnant coercivity over larger values of time-scale is proposed. The methods to determine dynamic coercivity and dynamic remnant coercivity by other researchers are summarized. The results of dynamic coercivity obtained by three methods on magnetic recording disks are compared. It is observed and concluded that the measurement of dynamic remnant coercivity is more suitable than measuring dynamic coercivity for most of the magnetic recording media.
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  • W.F. Lau, S.P. Wong, X.Y. Wu, N. Ke, W.Y. Cheung
    Type: Article
    Session ID: MMS2000-29
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Tetrahedral amorphous carbon (ta-C) films were prepared using a pulsed filtered vacuum arc deposition system at various substrate bias voltages. The Raman results confirmed that these ta-C films exhibited high sp^3 fraction of over 80%. The hardness, elastic modulus and compressive stress of the films were up to 47 GPa, 261 GPa and 17 GPa, respectively. The friction coefficient and wear rate of the films were as low as 〜0.085 and 4_x10^<-8> nm^3N^<-1>m^<-1>. The thermal stability of these films after vacuum annealing was also studied. The Raman results showed that the sp^3 fraction remained to be higher than 80% even after RTA at 900℃, meanwhile photoelasticity results showed that there was significant stress relaxation after annealing.
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  • M.F. Chiah, S.P. Wong, W.Y. Cheung, N. Ke, H. Wang, H. Liu, G.H. Wen, ...
    Type: Article
    Session ID: MMS2000-30
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    We have employed the pulsed filtered vacuum arc deposition technique to prepare Co-C and Fe-C nanocomposite films of various carbon compositions. Thermal annealing was performed in vacuum at various temperatures. Characterization of the as-deposited and annealed films was performed using various techniques including x-ray photoelectron spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), magnetic force microscopy (MFM) and magnetic measurements. The TEM results showed that the as-deposited Co-C films generally consist of amorphous Co nanograins of several nanometer in size encapsulated by amorphous carbon. After annealing, the Co grains become crystallized and were encapsulated by graphite carbon. Depending on the composition and annealing conditions, these films show very different magnetic properties. Superparamagnetism was observed in some of these films. For a sample with a composition of Co_<36>C_<64> the blocking temperature was determined to be 12K. Soft ferromagnetic properties with a coercivity of 2 or 3 Oe were observed for the as-deposited low Co composition films and they become magnetically harder after annealing. The domain structures of these Co-C and Fe-C films were observed by MFM and they showed different features.
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  • S.I. Pang, J.P. Wang, T.C. Chong
    Type: Article
    Session ID: MMS2000-31
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    In this study, CrAl was used as an underlayer and intermediate layer for CoCrPtTa thin film media on glass substrate. The magnetic properties of the media was improved as the Al content increases from 0 to 14 at% in CrAl underlayer. In-plane orientation of the magnetic layer could be achieved at lower substrate temperature by using CrAl instead of Cr underlayer. The magnetic properties could also be enhanced by using CrAl as an intermediate layer. It was found that CrAl underlayer and intermediate layer could reduce the magnetic switching volume, inter-grain interaction and improve crystallographic texture of the media.
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  • Toshiyuki Suzuki, Terumitsu Tanaka
    Type: Article
    Session ID: MMS2000-32
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Particulate media composed of small particles were studied in their high-density recording performances and thermal stability. Media include metal particulate media consisting of mean length of 71, 102 and 48 nm, and Ba ferrite particulate media consisting of mean thickness of 22, 28 and 50 nm. Using a loss-term simulation program, which takes into account gap-loss, spacing-loss and particle length loss, the recording capability (D_<20> of 265 kFRPI for MP and 290 kFRPI for Ba ferrite media) was estimated. Thermal stability was evaluated from the magnetization time decay measurement. It was found that MP media were stable and Ba ferrite media were less stable but within a practically allowable range.
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  • S.C. Oh, T.D. Lee
    Type: Article
    Session ID: MMS2000-33
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    In this study, effects of novel VMn underlayer on magnetic properties of CoCrPt/VMn longitudinal medium were studied and compared with those of CoCrPt/Cr medium. It was found that the VMn film had (200) preferred orientation and the lattice constant was about 0.2967 nm, which is slightly larger than that of the Cr, 0.2888 nm. The grain size of VMn film was 9.3 nm at 30 nm thickness, and this is about 38 % smaller than that of a similarly deposited Cr film. The CoCrPt/VMn films showed higher coercivity in comparison with the CoCrPt/Cr films. The coercivity increase seems to be attributed to the increased Co (11.0) texture, improved lattice matching between Co (11.0) and VMn (200) and lower stacking fault density. Mn must have diffused into the CoCrPt magnetic layer more uniformly rather than preferentially along grain boundaries and this reduced Ms at higher substrate temperature.
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  • Yang Shaoguang, Zhu Hao, Du Youwei
    Type: Article
    Session ID: MMS2000-34
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Anodic aluminum oxide (AAO) membranes with ordered nanochannel have been prepared as the disk for fabrication of patterned magnetic storage media. Metallic nanowire arrays have been prepared by electrodepositing the corresponding materials into pores of the AAO membranes. Magnetic property of the nanowire array reveals that this kind of array can be used as vertical recording media. The storage density of this media would reach 170 Gbit per square inch.
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  • Y.J. Tang, S.K. Wong, T.F. Hung, A.B. Pakhomov, C.Y. Wong
    Type: Article
    Session ID: MMS2000-35
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Cobalt-platinum alloy films have long been attractive as materials for permanent magnets due to their high magnetic anisotropy, high coercivity, and good corrosion resistance. Of continuing interests are the magnetization reversal mechanism and coercivity of such films for high-density magnetic recording media. In this article, Pt_3Co alloy films are produced using a sputtering system. To understand the reversal mechanism of Pt_3Co alloy films, the recoil loops from the major hysteresis loop have been measured. The reversible magnetization M_<rev> dependence of the irreversible magnetization M_<irr> exhibits a minimum when M_<irr> is slightly larger than zero, which is the characteristic of a material that contains domain walls bowing during reversal caused by localized pinning due to dipolar fields for the films. By analyzing the linear dependence of the coercivity on the anisotropy field at different temperatures, the strength of the local dipolar fields N_<eff> which jnfluences the creation of the reversed magnetic nucleus, is estimated. We found a positive value of N_<eff> which indicates that reversal process is mainly controlled by pinning due to local dipolar fields. It is also supposed that the dipolar fields originated from irregular local random anisotropy caused by residual stress, cavities, or inclusions, may be effective sources of pinning in the reversal process, and may strongly affect the coercivity of the film.
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  • Type: Appendix
    Pages App1-
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
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  • Type: Cover
    Pages Cover2-
    Published: November 14, 2000
    Released: June 23, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS
    Download PDF (65K)
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