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Displaying 1-23 of 23 articles from this issue
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Article type: Cover
Pages Cover1-
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (14K) -
Article type: Index
Pages Toc1-
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (94K) -
S.P. Wong, M.F. Chiah, W.Y. Gheung, N. Ke, Z.Q. Jin, X.Y. Wu, J.B. XuArticle type: Article
Session ID: VIR99-19
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSGranular thin films of Co_xAg_<1-x> and Fe_xAg_<-x> of various compositions were prepared using a pulsed filtered cathodic arc co-deposition system. The GMR effect in the temperature range from 20K to 300K and the domain structures in these films have been studied. Both the GMR effect and the domain structures of these films show similar features as those reported in the literature for films prepared using the sputter deposition technique. Our results show that the pulsed filtered arc co-deposition method is a promising technique for the fabrication of novel magnetic thin film structures.View full abstractDownload PDF (859K) -
Minoru HashimotoArticle type: Article
Session ID: VIR99-20
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSLinear signal analysis(LSA)is the conventional method of estimating the playback voltage and pulse width in linearly operating shieded GMR heads. To improve the accuracy of LSA, we developed a new, highly precise LSA which includes the effect of the distribution of magnetization in the medium and inhomogeneous biasing by domain control magnets. Utilizing this new LSA to calculate the playback waveforms, the calculated peak voltage and pulse width were compared with the experimental values and good agreement within 10% was obtained.View full abstractDownload PDF (643K) -
Bin Ma, Fulin Wei, Daishun Zheng, Dongping We, Zheng Yang, Mitsunori M ...Article type: Article
Session ID: VIR99-21
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSThe nanocrystallite Fe-Ta-N thin film with high Ta content were prepared by reactive sputtering. The dependence of structures and magnetic properties on P(N_2)and annealing were investigated by X-ray diffraction and VSM. It is found that Ta atoms replace Fe atoms of α-Fe lattice in nitrogen-free films, and a substituted solid solution is formed to the contrary. In nitrogened film the as-deposited films mainly consist of amorphous. After proper annealing, nanocrystallite α-Fe grains of(110)oriented crystallized fron the amorphous matrix. and excellent soft magnetic properties are obtained, due to the exchange coupling between nanocrystallite α-Fe grains.View full abstractDownload PDF (377K) -
Nguyen Anh Tuan, Nguyen Xuan Chanh, Nguyen Hoang LuongArticle type: Article
Session ID: VIR99-22
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSMagnetoresistive(MR)effect in the magnetic films are giving rise to vast application capacities for the super-high density information storage. Recently, much attention has been paid to the magnetoresistive granular(or heterogeneous)alloy films such as Co-Ag system. In this paper, we carried out studies of structural, magnetic properties and magnetoresistance of as-deposited and annealed magnetic granular Co_xAg_<100-x> alloy films prepared by rf cathode sputtering method with x varied between 12÷40 in some various technological conditions. The structure of these films was investigated by X-ray Diffraction(XRD), Atomic Force Microscopy(AFM), Electron Diffraction(ED)and Transmission Electron Microscopy(TEM)methods. Magnetic properties were measured using Vibrating Sample Magnetometer(VSM)and MR effect was detected with a conventional four-poing probe resistance measurement at room temperature in magnetic fields up to 14 kOe. Relations of the structural and magnetic properties with MR effect were discussed. Some of influence of technological conditions on MR were considered.View full abstractDownload PDF (980K) -
Liu Xiaoxi, Bai Jianmin, Wei Fulin, Yang Zheng, Akimitsu Morisako, Mit ...Article type: Article
Session ID: VIR99-23
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSWe have investigated the dependence of volume fraction and sputtering gas pressure on the particle size of Fe-Si-O granular systems. The Fe particle size is determined by fitting the Langevin function with the nagnetization curves of the films. The particle size is decreasing with the increase of sputtering gas pressure.View full abstractDownload PDF (277K) -
Hiroyuki Ikeda, Yuzo SeoArticle type: Article
Session ID: VIR99-24
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSAn effort to increase track density of hard disk drive faces difficulties that the recording area of the required servo signal becomes too large. Multi channel disk drive leads not only to higher transfer rate, but also allows a reduction in the servo recording area, since each channel can read a different servo pattern. In this paper, we describe the principle and experimental results of reduced servo burst systems. Optimization of servo burst recording and compensation of servo signal to omit reversed phase burst signals are also discussed. In addition, a reduced address mark code system for multi channel disk drives is introduced.View full abstractDownload PDF (884K) -
H. Yoshikawa, C. Baubet, A. Furuya, T. Tanabe, T. Ohkubo, M. Yamamoto, ...Article type: Article
Session ID: VIR99-25
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSWrite once recording was performed on a novel spinel/garnet multilayered optical disk. The novel disk structure consists of an oxidized magnetite underlayer, Bi-garnet recording layer, and a magnetitc reflective layer. The spinel underlayer was deposited to enhance the crystallization process of the garnet recording layer. We succeeded in obtaining carrier to noise ratio exceeding 50 dB when the mark were recorded at 685 nm, with a power of 14 mW and a velocity of 2 m/s. The high C/N is believed to be obtained by the crystallization process of the garnet recording layer resulting in gradual deformation of the top reflective layer. The novel disk structure, comprised only of oxides, requires no protective layer making it suitable for high-density surface recording optical media.View full abstractDownload PDF (461K) -
P. Gao, R.M. Lin, M.K. LimArticle type: Article
Session ID: VIR99-26
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSVibration studies have become increasingly important in the mechanical design of hard disk drives(HDDs)due to the ever-growing demand for storage density and access speed. In fact, it is anticipated that it is the vibration/dynamic characteristics of HDDs assemblies that will eventually pose a design limit to their performances, not the associated electronics whose designs are far more advanced. In this paper, the experimental method of measuring the head actuator vibration/dynamics under the actual operation condition was developed based on VPI laser sensor system. The representative vibration modes of of limiting serve bandwidth were analyzed and identified. The effect of actuator pivot assembly on dynamic behavior of head actuator system was studied. Furthermore, the vibration testings were done with the different disk rotating velocity. The new method for measuring radial runout of didk was introduced. The effect of radial runout of disk on vibration/dynamic characteristics of head actuator was investigated.View full abstractDownload PDF (438K) -
Seng Ghee Tan, Thomas Liew, Teck Ee Loh, Teck Seng LowArticle type: Article
Session ID: VIR99-27
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSBoth frequency and time domain analysis of glide signals from a PZT glide-slider flying over a laser zone textured thin film disk media was used to determine the many sources of slider excitation. The glide signal strength was particularly dependent on the velocity-induced laser bump excitation and the effect of the air-bearing stiffness over the laser zone. Peaks were found on the glide-avalanche curves that were traced to both the laser-bump induced resonance of the slider and the effect of the air-bearing over a laser textured zone. Laser bump excitation far from the slider's natural vibrational modes was found to reduce the power transfer to the slider through the air-bearing.View full abstractDownload PDF (740K) -
M. Lu, M. Matsumoto, F.L. Wei, J.P. Wang, Z.X. Ren, Z. YangArticle type: Article
Session ID: VIR99-28
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSIn this paper, the effect of mesh size on the equilibrium magnetization configurations and the switching behavior are calculated by employing cubic particles with numerical micromagnetics. The sizes of the cubic particles D are varied from 200Å to 600Å. Each particle is divided into 3×3×3.5×5×5, 7×7×7× and 9×9×9 cubic elements. respectively. The remanent state may change from flower state to vortex state at about 500 Å(3×3×3× case). 520 Å(5×5×5 case), 530Å(7×7×7 and 9×9×9 cases). For D<500Å, switching occurs by uniform rotation with different meshes. For 500Å<D<530Å, a finer mesh generates uniform rotation while a crude generates nonuniform rotation. The angular dependence of the coercivity field and switching field with different meshes are also given.View full abstractDownload PDF (625K) -
Won-Cheol Jeong, Byung-Il Lee, Seung-Ki JooArticle type: Article
Session ID: VIR99-29
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSAlthough few considerations have been made concerning the practical implications of multilevel approaches in memory design, there is a general consensus concerning its applicability in MRAM cells. The memory density can be enormously increased with the adoption of multilevel characteristic. We have previously described a new multilevel GMR MRAM cell[5], but the earlier structure has some problems such as separating the memory level, destructive readout and the use of incomplete pseudo spin valve MRAM mode etc[6]. In this work, the second generation of multilevel MRAM has been proposed. It consists of one sensing layer per storage layer. With the combinations of the storage laywrs, we can separate the memory states, so that the multilevel characteristic can be realized. Due to the use of one sensing layer per storage layer, multilevel MRAM with using the fully developed pseudo spin valve MRAM mode has been proved to be established.View full abstractDownload PDF (422K) -
Bin Ma, Fulin Wei, Rui He, Daishun Zheng, Zheng Yang, An Wang, Jianpin ...Article type: Article
Session ID: VIR99-30
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSInduced uniaxial anisotropy in nanocrystallite Fe-Ta-N soft magnetic thin film has been investigated. It was found that the uniaxial anisotropy can be induced by applying a magnetic field during deposition. The direction of the uniaxial anisotropy can be changed by sputtering condition or by annealing in magnetic field. The nitrogen atoms play an important rule in uniaxial anisotropy. The occupation and diffusion of nitrogen atoms in α-Fe lattice are lattice are the origin of inducing and changing uniaxial anisotropy.View full abstractDownload PDF (331K) -
Yong-Jin Cho, Hyung-Joon Kim, Won-Chul Jung, Byung-Il Lee, Seung-Ki Jo ...Article type: Article
Session ID: VIR99-31
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSSince large magnetoresistance(MR)effects were reported in FM/I/FM structured magnetic tunnel junction(MTJ)thin films, a lot of works have been performed on the MR characteristics of those films for advanced magnetic devices. Although MTJ thin films showed excellent MR properties such as tens of MR ratio, more reliable and stable formation of insulating layer has been remained as a obstruction for recently developed magnetic devices. Therefore, in this work, MR properties were characterized using FM/I/FM structured thin films as a function of formation conditions of Al Oxide insulating layer, which was reported as a good insulating layer in MTJ thin films.View full abstractDownload PDF (298K) -
Hyeong-Jun Kim, Byung-Il Lee, Seung-Ki JooArticle type: Article
Session ID: VIR99-32
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSGiant magnetoresistance(GMR)characteristics of NiFe/Cu/Co spin valve thin films, which were formed on Cu/Si(111, 4 degree tilt-cut)templates by a 3-gun magnetron sputtering system, have been investigated as a function of composition in NiFe layer. It was found that R-H curves of these thin films change drastically with the composition in NiFe layer so that perfectly square R-H curves were obtasined at 4 : 1 atomic ratio of Ni : Fe and sloped R-H curves at zero external magnetic fields were obtained at other atomic ratios of Ni : Fe. The change of R-H curves could be understood by a transition of magnetic anisotropy in NiFe layer with the compositional variation. Analysis of crystal structures and preferred orientations by pole figure measurement indicate that the changes of magnetic anisotropy and GMR characteristics are originated from the variation of magnetoelastic effect of thin films. It was believed that these various GMR characteristics could increase the potentials of NiFe/Cu/Co spin valve thin films for recently researched magnetic devices.View full abstractDownload PDF (417K) -
Jianjiang Wang, Yuan Xing Lee, Chong Tow GhongArticle type: Article
Session ID: VIR99-33
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSAbstract : This paper presents the noise analysis and performance of timing recovery loop which applies phaselocked loop(PLL)in its basic control structure in Multilevel Decision Feedback Equalization(MDFE)of the recording cnannel. Noise performance in PLL is studied and some results in MDFE timing recovery loop are achieved.View full abstractDownload PDF (715K) -
Terumitsu TANAKA, Kohei WAKAMIYA, Toshiyuki SUZUKIArticle type: Article
Session ID: VIR99-34
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSMeasuring the cross-track profiles of a microtrack created by DC erasing both sides of a recorded track, linear recording density dependence of write track fringe width and that of read track fringe width were successfully separated, both of which are usually observed in combination. It was clarified that when a thin film head is used for reading, read track fringe width increases as linear recording density decreases, while it remains almost constant when an MR head is used. It was also clarified that write head fringe width for a thin film inductive head is less dependent on linear recording density. Measurement using two types of thin film inductive heads showed that trimming of write head poles resulted in decrease of head field fringe width.View full abstractDownload PDF (459K) -
Liu Bin, Wang XinmeiArticle type: Article
Session ID: VIR99-35
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSA novel method to construct RLL-conform ECC, based on regular RLL encoder and regular ECC, is proposed. The(d, k)constraint and the error correction capability can be combined flexiby. The code is easy to construct with higher efficiency than earlier approaches. The asymptotical coding rate achieves the coding rate of the RLL code. Encoding and decoding procedures are straightforward. The application of such code in magnetic recording channel is illustrated by an example. The performance of the example scheme is estimated. A procedure is addressed to minimize the overhead of the bridging sequence in practical applications.View full abstractDownload PDF (405K) -
Toshihiro UEHARA, Keigo MAJIMA, Shoichiro OGAWA, Junji NUMAZAWAArticle type: Article
Session ID: VIR99-36
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSWe propose precise write-time compensation for nonlinear transition shift in magnetic tape recording using d=1 rjunlength-limited(RLL)code as a channel modulation. In this write-time compensation approach, the write current transitions having a transition within 3 bits earlier are shifted so as to minimize the transition shift of the readback signal. First, we precisely measured the nonlinear transition shift using a VCR. Next, based on this measurement, we simulated the effects of the write-time compensation, verifying them in recording experiments with a VCR. The results show that when the optimum read equalization is applied to the readback signal, this write-time compensation approach increases the eye height and eye width while improving the byte error rate by about two orders.View full abstractDownload PDF (642K) -
Weichun Ye, Bin Liu, Yuanxing LeeArticle type: Article
Session ID: VIR99-37
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSA new method to determine the write precompensation value based on the sample data obtained from MDFE and M2DFE channel was studied in our paper. three parameters were proposed as NLTS indicators. These indicators do not require complex computation or additional circuits. They are very sensitive to NLTS but not to other non-linear distortions including the amplitude asymmetry of MR head and the shift of sampling clock. They can be conducted on drive level that uses MDFE channels. They offer a more practical and cost-effective way determining the write precompensation value especially in the mass production and fine adjustment.View full abstractDownload PDF (706K) -
Kees A.Schouhamer ImminkArticle type: Article
Session ID: VIR99-38
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSThe construction of high-rate codes is far from obvious, as table look-up for encoding and decoding is an engineering impracticality. The usual approach is to supplement the p source bits with m=q-p bits. Under certain, usually simple, rules the source word is modified in such a way that the modified word plus supplement bits comply with the constraints. The information that certain modifications have been made is carried by the m supplement bits. The receiver, on reception of the word, will undo the modifications. In order to reduce complexity and error propagation, the number of bits affected by a modification should be as small as possible. We will survey some examples of code constructions.View full abstractDownload PDF (590K) -
Article type: Appendix
Pages App1-
Published: February 26, 1999
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (75K)
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