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1.
We report on the recording performance of discrete track patterned media fabricated by focused ion beam (FIB). We investigated performance over a small area by spinstand read/write testing. Discrete track patterned regions show smaller magnetic track width and better signal separation between adjacent tracks and therefore higher track density than that of nonpatterned continuous media as a result of reduced side fringe effect and edge noise. We found that, at a designed groove depth of 4-8 nm, the shallow FIB etched grooves already provide good isolation between adjacent tracks, indicating the superiority of ion beam induced modification of magnetic properties in film media over physical modification of disk surface topography. This has implications for discrete track recording and media fabrication.  相似文献   

2.
Sohn JS  Lee D  Cho E  Kim HS  Sul S  Lee BK  Lee M  Moon C  Park NC 《Nanotechnology》2011,22(3):035305
Discrete track magnetic recording media with a 60 nm track pitch and prewritten servo patterns were fabricated and tested for read/write performance, and a feasibility analysis of the embedded servo was performed. The fabrication process consisted of ultraviolet nanoimprint lithography (UV-NIL) and sequential ion beam etching on a conventional perpendicular magnetic recording medium. Magnetic patterns were written to the fabricated tracks at 700 kilo flux changes per inch (kFCI) using a spin stand and were read using magnetic force microscopy (MFM), with a resulting signal-to-noise ratio (SNR) of 12.15 dB. The servo pattern was also visualized with MFM. These results demonstrated the feasibility of writing to a 30 nm wide discrete data track and the workability of the embedded servo pattern.  相似文献   

3.
In perpendicular recording, substantial erasure of the stored data patterns can occur during the writing process. Among all those erasure processes, side-track erasure (STE) is one of the critical issues in drive head/media integration. Unlike the adjacent track erasure (ATE) process, the locations of the STE affected areas are often many tens of tracks away from the central writing track location. In this work, we report on an experimental investigation and quantification of the general attributes and the origins of the STE processes in various situations. Particularly, we thoroughly characterize some distinctive signatures and behaviors of STE processes by employing both the amplitude- and bit-error-rate-based STE measurement methods in combination with a novel magnetic force microscope characterization technique  相似文献   

4.
Discrete track media offers many potential recording advantages over conventional continuous media in hard disk drives. In this study, we present a novel fabrication process for discrete track perpendicular magnetic media via electron beam lithography, ion milling, and the use of a protective Al sacrificial layer. Physical characterization of the media confirms the process is able to produce patterned tracks with no damage to the media. Spin stand analysis verifies the disks are flyable and capable of recording sharp transitions without any degradation in the magnetic signal  相似文献   

5.
This paper reports on a novel spin-stand method to measure adjacent-track erasure (ATE). The method divides a track into multiple sectors and makes use of the built-in servo system to ensure a highly accurate, amplitude-based measurement. By arranging subtracks uniformly across the range of interest around a center track, a quasi-continuous, detailed ATE profile can be obtained. We discuss the various features of this profile and how they depend on such parameters as skew angle, write current, frequency, and flying height. We then compare the ATE performance of state-of-the-art longitudinal and perpendicular recording components under realistic test conditions, such as may be used for a 250 GB/platter 95 mm desktop drive. We show that the perpendicular head and media compare favorably to longitudinal ones even though the track width is much narrower  相似文献   

6.
Transition curvature is a growing concern for high tracks per inch application. Due to low resolution from the playback transducer in cross track direction, the characterization of the transition edge is very difficult. This situation increases the engineering difficulty for writer pole design optimization and recording performance analysis. We have derived a simple transition shape model to study the transition curvature quantitatively. The complicated transition edge is simplified into one curving parameter. With such simplification, we are able to relate the transition curving effect with the cross track profile. In this paper, we will discuss the concept and analytical derivation of this model. A particular H/M combination is studied and its transition curvature is estimated. Compared with magnetic force microscope and micromagnetic modeling, this new approach has potential to become a practical spinstand or even Hard disk drive measurement if the W/R nonlinear effects are minimized.  相似文献   

7.
 离散磁道式磁盘在与磁头瞬态接触过程中极易损坏.为改善离散磁道式磁盘的瞬态接触状况,采用有限元仿真方法,建立了平整化前后离散磁道式磁盘与磁头的瞬态接触模型,分析了平整化前后离散磁道式磁盘接触应力分布特点,研究了磁头冲击速度、径向速度、磁盘表面摩擦系数等接触条件及平整化对离散磁道式磁盘最大等效塑性应变、塑性应变总体积的影响.结果表明:磁头冲击速度、寻道速度增大均可导致磁盘最大等效塑性应变、塑性应变总体积增大;摩擦系数增大可增大磁道最大等效塑性应变、减小塑性应变总体积;在接触初期,平整化离散磁道式磁盘可以减小磁道最大接触应力,缓解应力集中现象;在接触全过程中,平整化离散磁道式磁盘可以减小磁道最大等效塑性应变及塑性应变总体积;平整化所用2种弹性模量等力学特性不同的填充材料,即磁道材料与类金刚石碳,对于磁道接触状况的改善作用区别较小.以上结论可为降低离散磁道式磁盘的破坏程度提供理论指导.  相似文献   

8.
Design of a manufacturable discrete track recording medium   总被引:3,自引:0,他引:3  
The potential benefits of patterning discrete tracks onto a disk for magnetic data storage have long been investigated. A practical process for manufacturing a cost-effective discrete track recording (DTR) medium has prevented such a disk from being introduced into a product. In this paper, a process utilizing nano-imprint lithography techniques to create a land and groove structure on the surface of a disk substrate will be described. Design considerations for the geometry of the structure, as well as of the magnetic write and read widths of the head, are discussed. Data showing the magnetic characteristics and recording performance of a DTR medium are also presented.  相似文献   

9.
Three-dimensional optical data storage is demonstrated in an initially homogenous volume by first recording a reflection grating in a holographic photopolymer. This causes the entire volume to be weakly reflecting to a confocal read/write head. Superposition of two or three such gratings with slightly different k-vectors creates a track and layer structure that specialized servo detection optics can use to lock the focus to these deeply-buried tracks. Writing is accomplished by locally modifying the reflectivity of the preexisting hologram. This modification can take the form of ablation, inelastic deformation via heating at the focus, or erasure via linear or two-photon continued polymerization in the previously unexposed fringes of the hologram. Storage by each method is demonstrated with up to eight data layers separated by as little as 12 microns.  相似文献   

10.
The track misregistration (TMR) required to achieve gigabit areal densities is calculated for a set of components based on the average bit error rate for a file. The average error rate is a statistical average, based on the TMR of the file, of the on-track and off-track error rate. The on-track and off-track error rates are dependent on squeeze from adjacent tracks. In this analysis, the average error rate is calculated using measured error rate profiles of the center track. For a file average soft error rate of 1×10-6, the results show, for a particular head/disk combination designed for gigabit recording and operating at a linear density of 158 kbpi, that a track pitch of 4.0 μm (3.35 ktpi) can be achieved with a TMR of 0.635 μm. Obtaining this TMR value in a file is one of the challenges to recording of 1 Gb/in2 in magnetic storage products  相似文献   

11.
In magnetic recording systems the side fringing fields of magnetic recording heads are responsible for crosstalk from adjacent tracks and eventually for partial erasure of adjacent tracks, thereby limiting the attainable track density. In this paper we derive analytical expressions for the magnetic field near the side of a recording head and calculate the cosine transform of the longitudinal field component, with the head side angle and gap length as parameters. The field of a head of zero width is also considered. Due to the side fringing field the written track is somewhat wider than the geometrical head width; the increase in width being approximately proportional to the maximum field strength in the recording medium and the head-to-medium distance. The amplitudeuof the read crosstalk signal from an adjacent, infinitesimally narrow track is calculated and it appears that it can be approximated byu/u_{0} = 0.5 exp (-2pi x/lambda), where u0is the on-track signal (with zero head-to-medium spacing),xis the distance between track and head side, and λ is the wavelength. Maximum track densities are calculated for a specified crosstalk-to-signal ratio and a given head width and wavelength. For a wavelength of 10 μm, a head width of 5 μm, and a crosstalk of -20 dB, the track density is limited to about 130 tracks/mm, assuming a track width equal to the head width. When the track is taken to be 5 μm wider than the head to account for the effects of the write process, no guardband at all is needed for -20 dB crosstalk and the limit to the track density is 100 tracks/mn.  相似文献   

12.
Based on the Tsuboi-Fushida-Wallace spacing loss law, reciprocity principle, and the principle of an image plane, a two-dimensional, head independent theory of the playback process has been developed for perpendicular magnetic recording (PMR) media with a soft magnetic underlayer (SMUL). An assumption that the reversible magnetic permeability of the recording media is equal to one gives results in a simple form. The article, while not addressing the effect of underlayer on write performances, demonstrates complications caused by the presence of the underlayer during readback.  相似文献   

13.
The trend of increasing areal density, i.e., the number of bits recorded in unit area of the media, continues in the hard disk drive (HDD) industry. This growth is sustained by increasing both the track density and bit density. The track density that can be achieved in a drive depends on many factors such as the dimensions of read/write head and the performance of the head positioning servomechanism. The higher the servo bandwidth, the better the precision achieved in controlling the position of the head. Most of the drives use an embedded servo scheme, which puts a physical constraint on the frequency at which the position error is sampled, and hence, on the achievable bandwidth. The need for a better position error sensing (PES) scheme is the motivation behind exploring alternative methods of servo encoding. This paper addresses different aspects of decoding position error from the dual-frequency servo bursts. It is shown, using both simulation and experimental results, that the proposed scheme offers a feasible solution for generating the PES signal in high-performance HDD.  相似文献   

14.
The spectra of disturbances and noises affecting precise servo positioning for ultrahigh-density storage in future hard disk drives are time-varying and remain unknown. In this paper, we propose an online iterative control algorithm that sets the measured position error signal (PES) into the servo system to achieve high track densities by minimizing the square of the H2-norm of the transfer function from nonrepeatable run-out (NRRO) disturbances to the true PES. It is not necessary to solve any algebraic Riccati equations and linear matrix inequalities. The algorithm constructs an online repeatable run-out estimator to extract NRRO components for gradient estimates, thereby preventing the controller parameters from being trapped in a local minima. Experimental results on a PC-based servo system for a spinstand show an improvement of 22% in 3sigma NRRO and suppression of baseline NRRO spectrum  相似文献   

15.
Magnetoresistive playback off bit patterned magnetic recording media is studied. Three playback configurations are compared: not shielded sensors, shielded sensors commonly used in magnetic recording systems, and shielded differential sensors. Influence of patterned medium parameters including bit-filling ratio, bit shape, bit position jitter, bit-size variation on the playback signal is studied. Playback signal amplitude, D50, and signal-to-noise ratio are used to compare different playback sensor configurations. It is found that in general, shielded differential readers offer superior performance as compared to both shielded single sensor readers and not shielded readers.  相似文献   

16.
Three types of perpendicular recording media were compared using simulations. Exchange coupled composite (ECC) type media could support minimum track pitches up to 18 nm less than a single layer medium, allowing significantly higher areal recording densities. The recording performance of all media was highly susceptible to grain-to-grain variations of uniaxial anisotropy Ku and, in the case of ECC media, to variations in the interlayer coupling strength. Areal densities of around 500 Gb/in2 should be achievable using current technologies, higher densities require improved manufacturing tolerances  相似文献   

17.
白雪  史宝军  贺磊  杨廷毅 《工程力学》2017,34(8):25-30,50
当硬盘工作时,磁头滑块飞行在高速旋转的磁盘上方,头/盘界面产生了一层只有几个纳米的气膜,该气膜润滑方程为考虑气体稀薄效应的修正Reynolds方程。为了提高磁记录密度,人们正在考虑用离散磁道(Discrete Track Recording,DTR)磁盘取代传统的光滑磁盘。由于这种DTR磁盘表面磁道和沟槽的影响,在数值求解修正Reynolds方程的过程中,就需要足够多的离散网格来分辨出DTR磁盘表面几何形状,从而带来了计算效率问题。基于均匀化理论和修正Reynolds方程的线性流率(Linearized Flow Rate,LFR)模型,该文推导了一个适合分析DTR磁盘气体润滑特性的均匀化Reynolds方程,并采用有限体积法对均匀化Reynolds方程进行了求解和验证。其结果显示:相对于修正Reynolds方程,求解均匀化Reynolds方程只需要很少的离散网格,从而节省了大量的计算时间,大幅提高了计算效率,且两者压力分布、压力中心和承载力的最大相对误差都小于3.5%。  相似文献   

18.
The existing magnetic data recording media employ polycrystalline tracks, on which data are encoded using domains with different orientations of magnetic moments. We have numerically simulated data recording on the track in a single crystal film, in which the domain structure is formed using an intrinsic magnetostatic field of the crystal and the Bloch domain walls play the role of information bits.  相似文献   

19.
An experimental digital VCR (DVCR hereinafter) was developed. The DVCR has two new technologies for reduction of tape consumption. One is a bit rate reduction technology of a component video signal down to around 25 Mbps and the other is a high density recording technology. The bit rate reduction technology is based on an 8×8/2×4×8 two dimensional DCT (Discrete Cosine Transform) and a VLC (Variable Length Coding) that completes over 5 macro blocks. Editing, trick plays and invisible error concealments also have been realized by this bit rate reduction while keeping the playback picture quality very high. The high density recording technology is based on ME tape and an ATF (Automatic Track Finding) system. A track pitch of 10 μm and a bit length on tape of 0.25 μm have been realized. The possibility of a higher linear recording density has been confirmed through theoretical analysis, simulations and experiments  相似文献   

20.
A technique for reducing cross-recording on data storage media with high track density is described. In order to detect cross-recording sensitively, an inverted mark pattern was first recorded on adjacent tracks and then synchronized with a normal recorded mark pattern on the central track. These patterns were repeatedly recorded as the recording power was increased. Readout signals of the recorded mark pattern were evaluated on the central track in each condition, and an optimum recording power was precisely determined from the maximum amplitude of the signals. When this new technique was applied to a magneto-optical disk, the bit error rate was reduced to less than 10-4. This is the first technique to reduce cross-recording by laser power only  相似文献   

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