The Experts below are selected from a list of 4365 Experts worldwide ranked by ideXlab platform

K Hono - One of the best experts on this subject based on the ideXlab platform.

  • high melting point metal pt w seed layer for grain size refinement of fept based heat assisted Magnetic Recording Media
    2019
    Co-Authors: Jian Wang, Ippei Suzuki, Y K Takahashi, K Hono
    Abstract:

    Refinement of the FePt grain size for heat-assisted Magnetic Recording (HAMR) Media was explored by utilizing high melting point metals Pt and W as seed layers. Unlike the W, the Pt seed layer promotes a good epitaxial growth and leads to a higher degree of L10-ordering in FePt films. It also substantially refines the FePt grains from big islands into smaller particles. For the FePt-C nanogranular film, the Pt seed layer improves the wettability and favors a single-columnar growth. Thus, the Pt seed layer provides a new valid approach to optimize the microstructure and Magnetic properties for next-generation FePt-based HAMR Media.

  • Heat-assisted Magnetic Recording Media materials
    2018
    Co-Authors: K Hono, Y K Takahashi, Jan-ulrich Thiele, Antony Ajan, Xiaomin Yang, Ricardo Ruiz, Lei Wan
    Abstract:

    Heat-assisted Magnetic Recording (HAMR) is being developed as the next-generation Magnetic Recording technology. High anisotropy granular Media such as FePt-C have been demonstrated as HAMR Media for ∼2 Tbpsi (terabits per in^2) Recording density. In order for this technology to reach its full potential of 4–5 Tbpsi, more progress and innovations are needed for the key requirements for HAMR Media, including microstructure, design, Magnetic distribution, and thermal design. Beyond granular Media, heated-dot Magnetic Recording (HDMR) is planned to extend areal density toward 10 Tbpsi. HDMR combines similar advanced Recording layer materials with advanced patterning techniques to fabricate <10-nm rectangular dot Media.

  • mechanism of coercivity enhancement by ag addition in fept c granular films for heat assisted Magnetic Recording Media
    2014
    Co-Authors: B Ch S D S Varaprasad, Jian Wang, Y K Takahashi, T Nakamura, W Ueno, K Nitta, Tomoya Uruga, K Hono
    Abstract:

    We investigated the Ag distribution in a FePtAg-C granular film that is under consideration for a heat assisted Magnetic Recording medium by aberration-corrected scanning transmission electron microscope-energy dispersive X-ray spectroscopy and X-ray absorption fine structure. Ag is rejected from the core of FePt grains during the deposition, forming Ag-enriched shell surrounding L10-ordered FePt grains. Since Ag has no solubility in both Fe and Pt, the rejection of Ag induces atomic diffusions thereby enhancing the kinetics of the L10-order in the FePt grains.

  • l1 _ 0 ordered fept based perpendicular Magnetic Recording Media for heat assisted Magnetic Recording
    2013
    Co-Authors: Bollapragada Varaprasad, Yoshihiro Takahashi, M Chen, K Hono
    Abstract:

    We update our continuous effort to optimize the microstructures and Magnetic properties of FePt-X granular films to achieve an ideal Media structure on glass substrates for heat-assisted Magnetic Recording. For segregant X, we investigated C, SiO2 , TiO2 and their mixtures. While FePt-C granular films show excellent inplane granular structure for the thickness (t) smaller than 6 nm, a second layer appears for t >; 6 nm. On the other hand, FePt-TiO2 granular film shows a columnar structure with a smooth surface, but the inplane morphology is interconnected. To enhance the phase separation and realize the laterally isolated columnar structure, we mixed the segregant materials of SiO2 or TiO2 with C. We also used the thin FePt-C films as templates for FePt-X(X=SiO2 and TiO2) since the FePt-C showed good particle separation with the fine particle size. Based on these experimental results, we discuss how to attain the ideal Media structure for heat-assisted Magnetic Recording.

  • l10 ordered feptag c granular thin film for thermally assisted Magnetic Recording Media invited
    2011
    Co-Authors: L Zhang, K Hono, Yoshihiro Takahashi, Barry Cushing Stipe, Jiayang Juang, M Grobis
    Abstract:

    We studied highly L10-ordered FePtAg–C nanogranular film as a potential high-density storage medium in thermally assisted Magnetic Recording (TAR). A 6.4-nm-thick FePtAg–C film with a perpendicular coercivity of 37 kOe and an average grain size of 6.1±1.8 nm was fabricated on oxidized silicon substrate with a 10 nm MgO interlayer at 450 °C. The time-dependence measurement of remnant coercivity showed the energy barrier of Eb = 7.6 eV ∼300 kBT at room temperature, meaning the excellent thermal stability for long-term data storage. Static tester experiments on this film using a TAR head demonstrate the feasibility of Recording at an areal density of ∼450 Gbits/in.2.

Naoki Honda - One of the best experts on this subject based on the ideXlab platform.

  • structure and Magnetic properties of co pt ta2o5 film for perpendicular Magnetic Recording Media
    2005
    Co-Authors: T Chiba, Jun Ariake, Naoki Honda
    Abstract:

    Abstract Co–Pt–Ta 2 O 5 film was investigated for perpendicular Magnetic Recording Media. Perpendicular coercivity of over 3 kOe was obtained when the film was deposited at high Ar gas pressure of 7 Pa, where Ta existed in a state of metal–oxide mixture in the film. It was indicated that grain isolation was obtained in the film. On the other hand, no increase in the coercivity was obtained by deposition introducing oxygen gas into Ar gas, although a fraction of oxidized Ta increased.

  • magnetization reversal process in polycrystalline ordered fe pt 001 thin films
    1999
    Co-Authors: Toshio Suzuki, Naoki Honda, Kazuhiro Ouchi
    Abstract:

    Magnetization reversal processes in Fe–Pt(001) thin films prepared by a high-pressure sputter deposition method were studied. Samples were classified in four types of domain patterns. Type I, with maze-like domain patterns, has a mixing mode of nucleation and wall motion for magnetization reversal. While, type II, with large island domain patterns, shows wall motion in its magnetization reversal. Type III has small island domain patterns, and type IV has fine discrete domain patterns showing rotational modes with inclined M–H loops. Type IV is expected to be one of the candidates for future ultrahigh-density Magnetic Recording Media with high resolution and low noise.

  • preparation of ordered fe pt thin films for perpendicular Magnetic Recording Media
    1999
    Co-Authors: Toshio Suzuki, Naoki Honda, Kiko Harada, K. Ouchi
    Abstract:

    Abstract A new preparation method of ordered Fe–Pt thin films with perpendicular Magnetic anisotropy was studied. Low-temperature ordering phenomenon was found at high Ar sputter-gas pressures. Extremely large perpendicular Magnetic anisotropy was obtained for a thin film using a glass substrate. Extending the method, further improvements of the Fe–Pt film have been made in terms of domain size. A very fine domain pattern was successfully observed, suggesting that the new Fe–Pt film will be expected to be a future ultrahigh density Recording medium.

Jiangang Zhu - One of the best experts on this subject based on the ideXlab platform.

  • quantitative transmission electron microscopy analysis of multi variant grains in present l10 fept based heat assisted Magnetic Recording Media
    2014
    Co-Authors: D E Laughlin, Jingxi Zhu, Andreas Kulovits, Jiangang Zhu
    Abstract:

    We present a study on atomic ordering within individual grains in granular L10-FePt thin films using transmission electron microscopy techniques. The film, used as a medium for heat assisted Magnetic Recording, consists of a single layer of FePt grains separated by non-Magnetic grain boundaries and is grown on an MgO underlayer. Using convergent-beam techniques, diffraction patterns of individual grains are obtained for a large number of crystallites. The study found that although the majority of grains are ordered in the perpendicular direction, more than 15% of them are multi-variant, or of in-plane c-axis orientation, or disordered fcc. It was also found that these multi-variant and in-plane grains have always grown across MgO grain boundaries separating two or more MgO grains of the underlayer. The in-plane ordered portion within a multi-variant L10-FePt grain always lacks atomic coherence with the MgO directly underneath it, whereas, the perpendicularly ordered portion is always coherent with the und...

  • multiple oxide content Media for columnar grain growth in l10 fept thin films
    2013
    Co-Authors: En Yang, D E Laughlin, Jiangang Zhu
    Abstract:

    An approach to enhance the height-to-diameter ratio of FePt grains in heat-assisted Magnetic Recording Media is proposed. The FePt-SiOx thin films are deposited with a decrease of the SiOx percentage along the film growth direction. When bi-layer and tri-layer Media are sputtered at 410 °C, we observe discontinuities in the FePt grains at interfaces between layers, which lead to poor epitaxial growth. Due to increased atomic diffusion, the bi-layer Media sputtered at 450 °C is shown to (1) grow into continuous columnar grains with similar size as single-layer Media but much higher aspect ratio, (2) have better L10 ordering and larger coercivity.

Eric E. Fullerton - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic and structural properties of FePt-FeRh exchange spring films for thermally assisted Magnetic Recording Media
    2004
    Co-Authors: Jan-ulrich Thiele, S. Maat, J. L. Robertson, Eric E. Fullerton
    Abstract:

    Recently a novel Media structure for thermally assisted Magnetic Recording was proposed consisting of a layer of FePt exchange coupled to a FeRh layer. The FePt forms a high magnetocrystalline anisotropy, high coercivity ferroMagnetic layer. The FeRh layer is antiferroMagnetic at room temperature, but upon heating above a transition temperature becomes ferroMagnetic with a large Magnetic moment and low magnetocrystalline anisotropy. The coupled ferroMagnetic FePt and FeRh layers form an exchange-spring system significantly lowering the coercive field of the composite system compared to a single layer of FePt. This feature opens intriguing possibilities for Media applications for thermally assisted Magnetic Recording where the ferroMagnetic phase of FeRh is exploited to help write the Media while the low-temperature antiferroMagnetic phase supports the long-term stability. Here temperature-dependent structural and Magnetic measurements of undoped and doped FeRh single layer and FePt-FeRh bilayer films are presented and the promises and challenges of the exchange spring Media structure are discussed.

  • ferh fept exchange spring films for thermally assisted Magnetic Recording Media
    2003
    Co-Authors: Jan-ulrich Thiele, S. Maat, Eric E. Fullerton
    Abstract:

    The temperature-dependent Magnetic response of exchange-coupled FePt/FeRh thin films is described. The FePt forms a high magnetocrystalline anisotropy, high-coercivity ferroMagnetic layer. The FeRh layer is antiferroMagnetic at room temperature but, upon heating above a transition temperature, becomes ferroMagnetic with a large Magnetic moment and low magnetocrystalline anisotropy, forming an exchange–spring system and significantly lowering the coercive field of the composite system. This feature opens intriguing possibilities for Media applications for thermally assisted Magnetic Recording where the ferroMagnetic phase of FeRh is exploited to help write the Media while the antiferroMagnetic phase supports the long-time stability.

  • dynamic coercivity measurements of antiferroMagnetically coupled Magnetic Media layers
    2001
    Co-Authors: J Lohau, Eric E. Fullerton, A Moser, David Thomas Margulies, M E Schabes
    Abstract:

    We have performed dynamic coercivity measurements on a series of antiferroMagnetically coupled (AFC) Magnetic Recording Media utilizing a static write/read tester. The samples consist of two Magnetic layers, which are antiferroMagnetically coupled by a nonMagnetic layer. The investigated samples have a fixed top layer thickness and variable bottom layer thickness, such that the composite remanent magnetization thickness product (MRtAFC) varies over a large range, 0.17–0.30 memu/cm2. We find that the ratio between anisotropy energy and thermal energy (≡ stability ratio, C−1), and the intrinsic switching field H0 are, within the experimental error, constant for the series. This suggests that the top Magnetic layer to first order determines the stability ratio of the AFC Media and that MRtAFC can be varied over a large range without decreasing the stability or increasing the write field requirements.

  • antiferroMagnetically coupled Magnetic Media layers for thermally stable high density Recording
    2000
    Co-Authors: Eric E. Fullerton, A Moser, David Thomas Margulies, M E Schabes, M J Carey, B A Gurney, Margaret Evans Best, Gabriel Zeltzer, Kurt A Rubin, H Rosen
    Abstract:

    We describe a Magnetic Recording Media composed of antiferroMagnetically coupled (AFC) Magnetic Recording layers as an approach to extend areal densities of longitudinal Media beyond the predicted superparaMagnetic limit. The Recording medium is made up of two ferroMagnetic layers separated by a nonMagnetic layer whose thickness is tuned to couple the layers antiferroMagnetically. For such a structure, the effective areal moment density (Mrt) of the composite structure is the difference between the ferroMagnetic layers allowing the effective Magnetic thickness to scale independently of the physical thickness of the Media. Experimental realizations of AFC Media demonstrate that thermally stable, low-Mrt Media suitable for high-density Recording can be achieved.

Toshio Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • magnetization reversal process in polycrystalline ordered fe pt 001 thin films
    1999
    Co-Authors: Toshio Suzuki, Naoki Honda, Kazuhiro Ouchi
    Abstract:

    Magnetization reversal processes in Fe–Pt(001) thin films prepared by a high-pressure sputter deposition method were studied. Samples were classified in four types of domain patterns. Type I, with maze-like domain patterns, has a mixing mode of nucleation and wall motion for magnetization reversal. While, type II, with large island domain patterns, shows wall motion in its magnetization reversal. Type III has small island domain patterns, and type IV has fine discrete domain patterns showing rotational modes with inclined M–H loops. Type IV is expected to be one of the candidates for future ultrahigh-density Magnetic Recording Media with high resolution and low noise.

  • preparation of ordered fe pt thin films for perpendicular Magnetic Recording Media
    1999
    Co-Authors: Toshio Suzuki, Naoki Honda, Kiko Harada, K. Ouchi
    Abstract:

    Abstract A new preparation method of ordered Fe–Pt thin films with perpendicular Magnetic anisotropy was studied. Low-temperature ordering phenomenon was found at high Ar sputter-gas pressures. Extremely large perpendicular Magnetic anisotropy was obtained for a thin film using a glass substrate. Extending the method, further improvements of the Fe–Pt film have been made in terms of domain size. A very fine domain pattern was successfully observed, suggesting that the new Fe–Pt film will be expected to be a future ultrahigh density Recording medium.