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Magnetics, IEEE Transactions on

Issue 5  Part 1 • Date May 2012

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  • [Front cover]

    Publication Year: 2012 , Page(s): C1
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  • IEEE Transactions on Magnetics publication information

    Publication Year: 2012 , Page(s): C2
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  • Table of contents

    Publication Year: 2012 , Page(s): 1689 - 1690
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  • Chairman's Preface

    Publication Year: 2012 , Page(s): 1691
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  • Technology Roadmap Comparisons for TAPE, HDD, and NAND Flash: Implications for Data Storage Applications

    Publication Year: 2012 , Page(s): 1692 - 1696
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (842 KB) |  | HTML iconHTML  

    This paper describes the roadmap goals for tape based magnetic recording (TAPE) and uses these goals as counterpoints for the roadmap strategies for hard disk drive (HDD) and NAND flash. Technology comparisons described in this paper will show that presently volumetric efficiencies for TAPE, HDD, and NAND are similar, that lithographic requirements for TAPE are less challenging than those for NAND and HDD, and that mechanical challenges (moving media and transducer to media separation) for TAPE and HDD are potential limiters for roadmap progress and are non-existent for NAND. One result of the technology comparison discussion will be that the potential for sustained annual areal density increase rates, i.e. extendibility, for TAPE, is significantly greater than that for NAND and HDD due to the present TAPE bit cell area being a factor of 200-300 larger than the NAND and HDD bit cell area. More critically, the roadmap landscape for TAPE is limited by neither thin film processing (i.e., nanoscale dimensions) nor bit cell thermal stability. In contrast, NAND volumetric density faces limitations in extending critical feature processing, now at 25 nm, and HDD volumetric density faces challenges in transitioning either to patterned media with critical feature processing well below 15 nm or to heat assisted magnetic recording (HAMR) with the introduction of laser components to the data write process. View full abstract»

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  • Two-Dimensional Magnetic Recording at 10 \hbox {Tb\its/\in}^{2}

    Publication Year: 2012 , Page(s): 1697 - 1703
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (871 KB) |  | HTML iconHTML  

    A shingled recording head design is proposed that makes use of a saturation magnetization gradient to focus flux into the corner of the writing pole. This design yields field gradients of 800 Oe/nm and can write more than 2.5 Tbits/in2 of user data onto a 10 nm thick ECC recording layer with 6 nm Voronoi grains. Maximum user densities are predicted to be over 4.66 Tbits/in2 with 8 nm grains and 12 Tbits/in2 with 5 nm grains using a perfect read and write scheme at a 1:1 bit aspect ratio. For read back, three contact dual differential MR head designs that have two independent free layers with magnetization pointing oppositely are examined for the purpose of extending magnetoresistive technology. The differential head shows good cross track resolution that will be advantageous at the low bit aspect ratios likely for two-dimensional magnetic recording. Results show that an array of three dual differential heads can successfully resolve an 8 nm track surrounded by adjacent tracks that have pseudo random bit sequences written to them, even though each head is wider than the track. View full abstract»

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  • Overcoming Super-Paramagnetism at Elevated Temperatures in HAMR

    Publication Year: 2012 , Page(s): 1704 - 1709
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    The idea behind heat assisted magnetic recording (HAMR) is to be able to reverse high anisotropy grains by heating them and consequently reducing their anisotropy. The high anisotropy grains are necessitated because of increased demands on density and consequent reduction in grain sizes. Elevated temperature does reduce the anisotropy of the grain but also increases the super-paramagnetic fluctuations. This puts a limit on how high the temperature can be raised and as a result on how low the anisotropy can be reduced. Here I show that by increasing the length of the grain and by allowing the grain to have multiple domains at elevated temperatures the un-reversing effect of super-paramagnetic fluctuations can be minimized. The domains do undergo toggling between their moments aligning and opposing the field. But due to the presence of multiple domains at-least one domain in the direction of the field exists. As the temperature reduces the field acts on the domain-wall which propagates and the grain undergoes reversal by wall propagation. View full abstract»

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  • Fabrication of \hbox {Fe}_{16}\hbox {N}_{2} Films by Sputtering Process and Experimental Investigation of Origin of Giant Saturation Magnetization in \hbox {Fe}_{16}\hbox {N}_{2}

    Publication Year: 2012 , Page(s): 1710 - 1717
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (884 KB) |  | HTML iconHTML  

    We present a systematic study to address a longstanding mystery in magnetic materials and magnetism, whether there is giant saturation magnetization in Fe16N2 and why. Experimental results based on sputtered thin film samples are presented. The magnetism of Fe16N2 is discussed systematically from the aspects of material processing, magnetic characterization and theoretical investigation. It is observed that thin films with Fe16N2+Fe8N mixture phases and high degree of N ordering, exhibit a saturation magnetization up to 2.68T at room temperature, which substantially exceeds the ferromagnetism limit based on the traditional band magnetism understanding. From X-ray magnetic circular Dichorism (XMCD) experiment, transport measurement and first-principle calculation based on LDA+U method, it is both experimentally and theoretically justified that the origin of giant saturation magnetization is correlated with the formation of highly localized 3d electron states in this Fe-N system. A large magnetocrystalline anisotropy for such a material is also discussed. Our proposed “cluster+atom” theory provides promising directions on designing novel magnetic materials with unique performances. View full abstract»

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  • Practical FeCo Films for Perpendicular Writer Pole

    Publication Year: 2012 , Page(s): 1718 - 1722
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1160 KB) |  | HTML iconHTML  

    An attempt is made in this publication to review various developments of FeCo films for recording heads in the last decade and to look at emerging developments regarding these films. A series of FeCo films from 100% Fe to 100% Co was sputter deposited, characterized, and analyzed for various magnetic properties such as magnetostriction, uniaxial anisotropy, coercivity, dispersion, and saturation magnetization. Many process parameters, with the most influencing parameter being sputter pressure, play an important role especially influencing dispersion and/or hard axis coercivity (Hch) in these materials. Out of the many developments to date the effect of seed layer(s) in reducing grain size of high moment bcc FeCo films is still intriguing and, hence, a comprehensive review and analysis of seed layer effects are included. Although film stress can play an important role in optimizing Hch, there is no clear trend seen between film stress and Hch when viewed across broad processing conditions. Higher Hk evolution with oblique deposition is an interesting phenomenon in these films. Uniaxial anisotropies of nearly 1000 Oe were found. The anisotropy evolution is explained through magnetoelastic energy and through crystal structure. Even though these films are very columnar in nature it was found that there was little to no fiber texture present in these films and there was no difference in texture between fine grained and coarse grained FeCo films. View full abstract»

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  • Micromagnetic Model Analysis of Planar Type Recording Write Heads for High Transfer-Rate Recording

    Publication Year: 2012 , Page(s): 1723 - 1730
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1377 KB) |  | HTML iconHTML  

    Planar type recording write heads were investigated using a micromagnetic analysis targeting a transfer-rate of 5 GHz. Six different planar head structures with various yoke widths, yoke heights, and coil locations were modeled. Six different conventional single-pole-type (SPT) write heads were also used for comparison. The material characteristics including the exchange constant, anisotropy energy, and Gilbert damping factor were also varied. It was found that the planar heads had a faster high-frequency response, a larger recording field, and a smaller ATE field. In the planar head, the most dominant factor for high transfer-rate recording was the coil location relative to the main pole tip and the return yoke height, while the yoke width was less important. Because the multi-turn coil can be realized with a wide yoke, it is advantageous in the planar head. With regard to the material characteristics, a small Gilbert damping factor was the most effective, while the other material characteristics did not yield significant differences. View full abstract»

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  • Advanced Micromagnetic Analysis of Write Head Dynamics Using Fastmag

    Publication Year: 2012 , Page(s): 1731 - 1737
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (878 KB) |  | HTML iconHTML  

    Magnetization and magnetic field dynamics arising when switching a realistic recording head model is studied. The write head design comprises a return pole, yoke, main pole, tapered trapezoidal pole tip, tapered wrap around shield (WAS), and soft underlayer. The analysis was performed using the high-performance micromagnetic simulator FastMag, which is well suited for the write head dynamic problems due to its ability to handle complex magnetic devices discretized into many millions of elements. The head dynamics is considered for different mesh densities, switching data rates, and current waveforms. It is demonstrated that improper discretization may result in a very different magnetization behavior. This is especially pronounced for cases of high switching rates, for which meshes of insufficient density resulted in a completely incorrect behavior, e.g. absence of switching. On the other hand, sufficiently dense meshes resulted in reliable dynamics and switching behavior. Furthermore, magnetization dynamics effects in WAS and their effects on the magnetostatic fields in the media layer were studied. WAS significantly improves the head field gradients in both down- and off-track directions, which is important for high areal recording densities. However, the presence of WAS leads to reduced write fields below the pole tip and to significant undesired magnetostatic fields below the side shields in the media layer. Such undesired fields can be obtained close to the pole tip as well as far from the tip. These phenomena result from the domain wall creation, propagation, and annihilation in WAS due to the switching. The field close to the pole tip can result in adjacent track erasure, while fields far from the tip can lead to far track erasure. The existence of these fields should be accounted for when performing recording system design optimization and analysis. View full abstract»

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  • Writer Footprint Measurement on Spinstand and Media Transition Curvature Characteristics

    Publication Year: 2012 , Page(s): 1738 - 1743
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1820 KB) |  | HTML iconHTML  

    The head media integration played a very important role to push up the areal density of perpendicular recording successfully. Besides the success of good sensitivity and high resolution reader at desired feature size of recording bit, the advanced writing process is the key enabler to sustain the areal density growth continuously. The sharper field gradient of writer and the narrower switching field distribution of recording media improve the transition jitter and promote the SNR of recording media. Without reducing grain size, the areal density of perpendicular recording has been increased by a few times. In this work, we investigate the performance of writing process via the measurement of head field footprint in recording media on the Spinstand. The feature size variations of head footprint at different writing current and different flying height (FH) illustrate the effective writing process visually. The transition curvature with transition width value at the trailing edge of writer pole is the key indicator to show the linear density capability related to writing process. View full abstract»

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  • CPP GMR Through Nanowires

    Publication Year: 2012 , Page(s): 1744 - 1750
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3454 KB) |  | HTML iconHTML  

    All-metal current perpendicular to the plane (CPP) giant magnetoresistance (GMR) layers have been made within insulating matrices by direct growth to avoid sidewall damage that is caused by lithographical patterning in current vacuum-deposited devices. These insulating matrices can be made to have nanostructures with multiscale order to allow photolithographical alignment of contacts to 10-500 nm devices. This alignment was demonstrated with 100-200 nm diameter structures to prove feasibility. Next, trilayers of [Co(15 nm)/Cu(5 nm)/Co(10 nm)] with 10 nm diameters were made by electrochemical deposition with 30 Ω resistance and 19% magnetoresistance. These parameters are desirable for read head sensors, especially because the nanowires described here have 1:1 aspect ratios, 10× smaller areas, and 100× lower resistances than conventional read sensors based on lithographically-produced magnetic tunnel junctions. Finally, the potential application of closely spaced arrays of CPP GMR sensors for enabling one-pass two dimensional recording as well as a new technique called cross recording will be discussed. View full abstract»

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  • Co-Based Heusler Alloys for CPP-GMR Spin-Valves With Large Magnetoresistive Outputs

    Publication Year: 2012 , Page(s): 1751 - 1757
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB) |  | HTML iconHTML  

    We studied various Heusler alloy compositions for the ferromagnetic layers of current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) spin-valves (SVs) to obtain large MR outputs for the read sensor applications. The exchange biased SV with Co2 Fe(Al0.5 Si0.5) alloy showed a resistance change-area product (ΔRA) of 6 m Ωμm2 and an MR ratio of 21% at room temperature when the Co2 Fe(Al0.5 Si0.5) layer was well-B2-ordered by a high temperature annealing at 500°C. The critical bias current density for the spin torque effect on the reduction of ΔRA was ~ 3 × 107 A/cm2. Based on the high spin polarization directly measured by the point contact Andreev reflection method, Co2 (Cr0.1 Fe0.9 )Si, Co2 Mn(Ga0.5 Sn0.5 ), and Co2 Fe(Ge0.5 Ga0.5) alloy thin films were investigated for CPP-GMR SVs. Among them, the Co2Fe(Ge0.5Ga0.5) alloy showed a high CPP-GMR ratio in the pseudo SVs exceeding 40% at RT and 120% at 10 K. View full abstract»

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  • Simulations and Experiments Toward High-Data-Transfer-Rate Readers Composed of a Spin-Torque Oscillator

    Publication Year: 2012 , Page(s): 1758 - 1764
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (883 KB) |  | HTML iconHTML  

    High-data-transfer-rate readers beyond 3 Gbit/s composed of spin-torque oscillators (STOs) are considered and the signal-to-noise ratios (SNRs) of the output signals under the thermal magnetization fluctuations are calculated by using the recent nonlinear theories. The “STO Reader” senses the media field as a modulation in the oscillation frequency, enabling high-data-transfer rates beyond the limit of ferromagnetic relaxation. The output (digital) signal is obtained by frequency modulation (FM) detection, which is commonly used in communication technologies. As the problem of rapid phase diffusion in nonlinear STOs caused by the thermal fluctuations is overcome by employing a delay detection method, the sufficiently large SNRs are expected even in nonlinear STOs less than 30×30 nm2 in size. The prompt response of the STO frequency (phase) to the media field and the high-data-transfer rate beyond 5 Gbit/s are shown by micromagnetic simulation. The frequency transition of STO in less than 1 ns under the pulse field is also confirmed by experiment. View full abstract»

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  • FePt as Read Sensor Hard Bias Material

    Publication Year: 2012 , Page(s): 1765 - 1769
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB) |  | HTML iconHTML  

    A low temperature chemical ordering approach was presented for L10 phase FePt alloy's application in read sensor hard bias. We show that platinum seed and cap layers together can help the iron-rich FePt layer to achieve A1 to L10 phase transformation at temperatures as low as 300 °C. For platinum-rich FePt alloy iron seed and cap layers are effective in promoting its phase transformation. Element cap and seed together are more effective to obtain high coercivity than either of them alone. In order to implement FePt permanent magnet in transducer product, new thermal processes and sequences are needed. View full abstract»

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  • Self-Biased Differential Dual Spin Valve Readers for Future Magnetic Recording

    Publication Year: 2012 , Page(s): 1770 - 1776
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    For future magnetic recording, one challenge is that the shield to shield spacing (SSS) of readers cannot be scaled down to achieve the linear density requirement. A differential dual spin valve (DDSV) has been proposed to improve the linear resolution as it does not rely on the magnetic shields to diminish the interference from adjacent bits. The side reading becomes more and more challenging as the track width shrinks to below SSS to accommodate high track density, in particular for a DDSV reader in which no magnetic shield or larger SSS is used. A self-biased DDSV structure is proposed to replace the conventional abutted junction stabilization scheme. In the self-biased DDSV readers, two side shields are put at the both sides of the sensor across the track direction in the replacement of the hard bias (HB). The stray fields from the two free layers in the DDSV sensor bias each other to stabilize the domain structure of the free layers. Preliminary analysis shows that the self-bias DDSV is also robust against the spin torque-induced magnetic instability. Simulation results indicate that the self-biased DDSV reader has much better reading sensitivity for the opposing fields generated by magnetic transitions than HB-stabilized sensor. It is found that for DDSV readers, the mag-noise is less significant due to a larger signal field and thicker free layer. Current perpendicular to the plane (CPP)-DDSV sensors have been fabricated and show very good differential effect in the real operating mode. The magnetoresistance performance of individual spin valve in CPP-DDSV sensors has been obtained through measurements with applied field and pinning field parallel to the easy axis of the free layer. View full abstract»

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  • Data Handling Algorithms For Autonomous Shingled Magnetic Recording HDDs

    Publication Year: 2012 , Page(s): 1777 - 1781
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB) |  | HTML iconHTML  

    The acceptance of shingled magnetic recording (SMR) drives in the marketplace depends in part upon their system performance with the operational constraints demanded by SMR's wide writing heads. Current thinking suggests that SMR may require significant changes to the host file system because of SMR's natural proclivity for sequential writing, and supposed difficulty with random write operations. In this work, we propose a data handling algorithm which exhibits good short-block sustained random write performance. In addition, we examine optimal algorithms for intermediate transfer lengths on the order of one physical track in length. View full abstract»

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  • Study on High-Frequency 3–D Magnetization Precession Modes of Circular Magnetic Nano-Dots Using Coplanar Wave Guide Vector Network Analyzer Ferromagnetic Resonance

    Publication Year: 2012 , Page(s): 1782 - 1788
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1236 KB) |  | HTML iconHTML  

    Ferromagnetic resonance (FMR) modes for Fe70Co30 magnetic nano-dots of 100 nm in diameter in a mono-domain state are studied under different in-plane and out-of-plane magnetic fields using a reflection measurement from a vector network analyzer with a coplanar wave guide (CPW VNA FMR) and a micromagnetics simulation. The observed real and imaginary parts of the reflection signal become a combination of symmetric and antisymmetric Lorentzian forms in FMR. The combinations are given different susceptibility components of χxx and χzx by changing the sample position on the CPW. The magnetic dots exhibit triple modes in FMR spectra from an influence of the demagnetization field distribution in the mono-domain state. The magnetic dots also show a different variation of FMR amplitude in χxx and χzx for an out-of-plane field increase. View full abstract»

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  • Relationship Between Near Field Optical Transducer Laser Absorption and Its Efficiency

    Publication Year: 2012 , Page(s): 1789 - 1793
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    Heat-assisted magnetic recording (HAMR) has shown its promising application for recording density beyond 1 Tb/in2 . However, the reliability/lifetime of the near field optical transducer is a big challenge. The temperature rise of the transducer is one of the reasons that lead to its failure. In this paper, the laser absorption of the transducer is investigated compared with the transducer efficiency (high efficiency is one of the main targets in the transducer design). The results show that with a fix medium and fix transducer material, high efficiency is always accompanied by high laser absorption which could be 10-25%. High efficiency and low absorption can be obtained by optimizing the medium properties and using transducer material with low refractive index. With the built HAMR head model, the transducer temperature rise is evaluated. The results show that the transducer temperature increase depends on the absorbed power, its size, and the space between the transducer and magnetic pole. The space affects the transducer temperature rise more seriously in large transducer size. Big size is preferable for the transducer to reduce its temperature increase. View full abstract»

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  • Magnetization switching in energy assisted recording

    Publication Year: 2012 , Page(s): 1794 - 1800
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1365 KB) |  | HTML iconHTML  

    Magnetization switching in energy assisted recording is examined using micromagnetic simulations. Heat assisted and microwave assisted recording are compared. The high frequency magnetic field used in microwave assisted recording can be used to reduce the switching field or the switching time, but the optimum frequencies have opposite trends as a function of temperature. In heat assisted recording the switching times at temperatures near to the Curie temperature are about half the room temperature value. In recording simulations heat assisted recording was able to write the highest quality tracks and has the potential to be able to write on media with much higher anisotropy than microwave assisted recording. View full abstract»

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  • Surface-Plasmon Resonance Characterization of a Near-Field Transducer

    Publication Year: 2012 , Page(s): 1801 - 1806
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1031 KB) |  | HTML iconHTML  

    Surface-plasmon resonance of a lollipop near-field transducer integrated in a planar solid immersion mirror for heat-assisted magnetic recording has been studied by a pump-probe photo-thermal measurement without medium coating and by recording on a phase-change medium. The resonant behaviors, including the resonant wavelength, the Q factor, on and off resonance photo-thermal signal, are consistent with our simulations. For lollipops of 190 nm in disk diameter and 20 nm thick, there are two resonant modes in the measured spectroscopic range (710 nm-950 nm). Recording on a phase-change medium shows that the wavelength of the short resonant mode is not sensitive to the presence of the medium while the wavelength of the long resonant mode exhibits significant red-shift. On resonance, the plasmon efficiency enables the pronounced near-field transducer recording. View full abstract»

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  • A Novel Approach of Carbon Embedding in Magnetic Media for Future Head/Disk Interface

    Publication Year: 2012 , Page(s): 1807 - 1812
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1147 KB) |  | HTML iconHTML  

    A novel method of carbon embedding (≤1 nm) is used as a surface modification technique to produce overcoat free media surfaces. The filtered cathodic vacuum arc technique at ion energy of 90 eV is used to embed carbon in the top surface of a ~25 nm iron/platinum (FePt) film. Transport of ions in matter (TRIM) simulations and X-ray photoelectron spectroscopy (XPS) are used to study carbon embedding profiles and surface chemical composition. XPS results show that carbon embedding is effective in improving the oxidation resistance of FePt. Conductive atomic force microscopy (CAFM) is done on samples after exposure to a 780 nm IR laser with an effective output power of 40 mW to study the thermal stability. No change in the conductivity is observed in the case of carbon embedded FePt surface. Ball-on-disk tribological tests are conducted at a contact pressure of 0.26 GPa on bare and modified FePt surfaces. It is observed that the coefficient of friction is reduced considerably from a value of approximately 0.8 to ~0.27 after the surface modification. View full abstract»

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  • Experimental Study of Lubricant Depletion in Heat Assisted Magnetic Recording

    Publication Year: 2012 , Page(s): 1813 - 1818
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB) |  | HTML iconHTML  

    Heat assisted magnetic recording (HAMR) is a promising choice to overcome the superparamagnetic limit in magnetic recording and further increase the areal recoding density of a hard disk drive. However, HAMR brings about serious lubricant depletion problems on the disk surface due to the high temperature in the heat assisted writing process. Experimental studies of the lubricant depletion under HAMR conditions are still very limited so far. It is essential to do experimental studies under real HAMR conditions or under equivalent conditions if a stand-alone laser is used to emulate the HAMR system. In this work, a self-developed HAMR tester is introduced. A method to control the repeatability of laser heating temperature is explained. Lubricant depletion, accumulation, loss, the percentage of accumulation to depletion, and the depth of depletion are determined quantitatively. The effects of laser power, total laser-on-time and laser-off-time in one laser heating and cooling cycle on lubricant depletion are studied experimentally with the HAMR tester. From the experimental studies, it is found that lubricant accumulation at the edge of the lubricant depletion track takes a considerable percentage of the lubricant depletion and the lower the laser heating temperature, the higher the percentage is. Furthermore, media cooling time plays a significant role in lubricant depletion for the media without a heat sink layer and on glass substrate. View full abstract»

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  • Bi-Directional Pattern-Dependent Noise Prediction for Heat-Assisted Magnetic Recording With High Jitter Noise

    Publication Year: 2012 , Page(s): 1819 - 1825
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (919 KB) |  | HTML iconHTML  

    In this paper, we first report the results of an investigation of perpendicular heat-assisted magnetic recording (HAMR) channels containing high jitter noise that is likely to be the case at very high areal densities (e.g., 4 Tb/in2). To model the HAMR channel, we use the thermal Williams-Comstock model and the microtrack model to derive the transition response, without large thermal spot approximation. Further, we propose a novel bi-directional pattern-dependent noise prediction (biPDNP) detector to improve the performance of the HAMR channel under high jitter noise conditions. The biPDNP detector utilizes backward linear prediction in the noise prediction process, as well as the conventional forward linear prediction. At bit error rate of 10-3, biPDNP detector offers 0.6-1.4 dB performance gain over the conventional PDNP detector. View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology