Relevant bibliographies by topics / Bit Patterned Media (BPM)

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Bit Patterned Media (BPM)'

Author: Grafiati
Published: 4 June 2021
Last updated: 4 February 2022

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Journal articles on the topic "Bit Patterned Media (BPM)"

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Kaewrawang, Arkom. "L10-CoPt Bit Patterned Media with Tilted Easy Axis for Ultrahigh Areal Density over 2.5 Tb/in2." Advanced Materials Research 931-932 (May 2014): 1255–59. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1255.

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Ultrahigh areal density is the key target of hard disk drive technology. Hence, writing field strength from head and switching field, Hsw, of media should be improved. In this work, we propose the one of alternative method to increase data density and reduce Hsw of the media by using tilted easy axis technology for bit patterned media (BPM) at areal density beyond 2.5 Tb/in2. Moreover, transition noise and superparamagnetic limit have been eliminated owing to characteristics of BPM. The effect of exchange coupled between adjacent bits, Adot, of tilted easy axis of BPM is analyzed by micromagnetic simulation software - the object oriented micromagnetic framework based on Landau-Lifshitz-Gilbert equation. The BPM with tilted easy axis perform clearly the reduction of Hsw below perpendicular media and available writing head field. The Adot of BPM has no effect on decreasing Hsw. Anisotropy and Zeeman energy density of BPM with tilted easy axis are higher and lower than perpendicular BPM, respectively. Thereby, BPM with tilted easy axis have high potentiality to improve Hsw of media at ultrahigh data density.
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Li, X. G., Z. J. Liu, A. G. Kang, and X. Y. Xie. "Writing Field Analysis for Shingled Bit-Patterned Magnetic Recording." Journal of Nanomaterials 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/4254029.

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A novel method utilizing response surface methodology (RSM) is proposed for effective analysis of the combined influence of writing head geometry and media properties on writing field performance. The method comprises two main modules: (1) a parametric writing head model based on finite element electromagnetic field analysis and (2) an effective writing field gradient model based on RSM. Using the method proposed, the writing performance of an asymmetrically shielded writing head for shingled magnetic recording on bit-patterned media (SMR-BPM) is analyzed. The results show that the shielding trailing gap and medium coercivity primarily impact the effective writing field (EWF) gradient and that the shielding side gap has a secondary impact. More importantly, the analysis shows a strong interaction effect between the influences of writing head geometry and medium coercivity on the EWF gradient, which indicates the need for inclusive design.
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Tipcharoen, Warunee, Arkom Kaewrawang, and Apirat Siritaratiwat. "Design and Micromagnetic Simulation of Fe/L10-FePt/Fe Trilayer for Exchange Coupled Composite Bit Patterned Media at Ultrahigh Areal Density." Advances in Materials Science and Engineering 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/504628.

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Exchange coupled composite bit patterned media (ECC-BPM) are one candidate to solve the trilemma issues, overcome superparamagnetic limitations, and obtain ultrahigh areal density. In this work, the ECC continuous media and ECC-BPM of Fe/L10-FePt/Fe trilayer schemes are proposed and investigated based on the Landau-Lifshitz-Gilbert equation. The switching field,Hsw, of the hard phase in the proposed continuous ECC trilayer media structure is reduced below the maximum write head field at interlayer exchange coupling between hard and soft phases,Aex, higher than 20 pJ/m and its value is lower than that for continuousL10-FePt single layer media andL10-FePt/Fe bilayer. Furthermore, theHswof the proposed ECC-BPM is lower than the maximum write head field with exchange coupling coefficient between neighboring dots of 5 pJ/m andAexover 10 pJ/m. Therefore, the proposed ECC-BPM trilayer has the highest potential and is suitable for ultrahigh areal density magnetic recording technology at ultrahigh areal density. The results of this work may be gainful idea for nanopatterning in magnetic media nanotechnology.
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Huda, Miftakhul, Zulfakri bin Mohamad, Takuya Komori, You Yin, and Sumio Hosaka. "Fabrication of CoPt Nanodot Array with a Pitch of 33 nm Using Pattern-Transfer Technique of PS-PDMS Self-Assembly." Key Engineering Materials 596 (December 2013): 83–87. http://dx.doi.org/10.4028/www.scientific.net/kem.596.83.

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The progress of information technology has increased the demand of the capacity of storage media. Bit patterned media (BPM) has been known as a promising method to achieve the magnetic-data-storage capability of more than 1 Tb/in.2. In this work, we demonstrated fabrication of magnetic nanodot array of CoPt with a pitch of 33 nm using a pattern-transfer method of block copolymer (BCP) self-assembly. Carbon hard mask (CHM) was adopted as a mask to pattern-transfer self-assembled nanodot array formed from poly (styrene)-b-poly (dimethyl siloxane) (PS-PDMS) with a molecular weight of 30,000-7,500 mol/g. According to our experiment results, CHM showed its high selectivity against CoPt in Ar ion milling. Therefore, this result boosted the potential of BCP self-assembly technique to fabricate magnetic nanodot array for the next generation of hard disk drive (HDD) due to the ease of large-area fabrication, and low cost.
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Kaewrawang, Arkom. "Effects of Magnetic Properties of L10-CoPt based Bit Patterned Media with Tilted-Easy Axis on Switching Field at Areal Density over 2 Tb/in2." Applied Mechanics and Materials 781 (August 2015): 207–10. http://dx.doi.org/10.4028/www.scientific.net/amm.781.207.

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Decrease of a switching field, Hsw, of the magnetic media with high magnetocrystalline anisotropy constant, Ku, can be handled by tilted-easy axis. Not only tilting easy direction of crystal but also optimum magnetic properties can improve writability. The effects of Ku and saturation magnetization, Ms, of L10-CoPt material of BPM with 45° tilted-easy axis are investigated in this article. The object oriented micromagnetic framework package based on Landau - Lifshitz - Gilbert equation has been used to analyze the magnetic properties of media in this paper. The results indicate that the Hsw decreases with decreasing Ku and increasing Ms. To achieve the Hsw lower than the maximum write head field, the Ku and Ms values should not be over 1.30 MJ/m3 and should exceed 0.30 MA/m, respectively.
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Brombacher, C., M. Grobis, J. Lee, J. Fidler, T. Eriksson, T. Werner, O. Hellwig, and M. Albrecht. "L10FePtCu bit patterned media." Nanotechnology 23, no. 2 (December 14, 2011): 025301. http://dx.doi.org/10.1088/0957-4484/23/2/025301.

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Guo, Shanshan, Feng Xu, Baomin Wang, Ning Wang, Huali Yang, Pravarthana Dhanapal, Fei Xue, Junling Wang, and Run-Wei Li. "Bit Patterned Media: 2D Magnetic Mesocrystals for Bit Patterned Media (Adv. Mater. Interfaces 21/2018)." Advanced Materials Interfaces 5, no. 21 (November 2018): 1870102. http://dx.doi.org/10.1002/admi.201870102.

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Krone, P., D. Makarov, T. Schrefl, and M. Albrecht. "Exchange coupled composite bit patterned media." Applied Physics Letters 97, no. 8 (August 23, 2010): 082501. http://dx.doi.org/10.1063/1.3481668.

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Yawshing Tang, Kiseok Moon, and Hyung Jai Lee. "Write Synchronization in Bit-Patterned Media." IEEE Transactions on Magnetics 45, no. 2 (February 2009): 822–27. http://dx.doi.org/10.1109/tmag.2008.2010642.

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XiaoMin Yang, Yuan Xu, Kim Lee, Shuaigang Xiao, D. Kuo, and D. Weller. "Advanced Lithography for Bit Patterned Media." IEEE Transactions on Magnetics 45, no. 2 (February 2009): 833–38. http://dx.doi.org/10.1109/tmag.2008.2010647.

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Dissertations / Theses on the topic "Bit Patterned Media (BPM)"

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Zygridou, Smaragda. "Fabrication and characterisation of L10 ordered FePt thin films and bit patterned media." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/fabrication-and-characterisation-of-l10-ordered-fept-thin-films-and-bit-patterned-media(838fa936-fad2-422a-a1dc-ab852f77b6a6).html.

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Highly ordered magnetic materials with high perpendicular magnetic anisotropy (PMA), such as the L10 ordered FePt, and new recording technologies, such as bit patterned media (BPM), have been proposed as solutions to the media trilemma problem and provide promising strategies towards future high-density magnetic data storage media. L10 ordered FePt thin films can provide the necessary high PMA. However, the ordering of this material perpendicular to the plane of the films remains challenging since high-temperature and time-consuming processes are required. In this work, a remote plasma sputtering system has been used for the investigation of FePt thin films in order to understand if the greater control of process parameters offered by this system can lead to enhanced ordering in L10 FePt thin films at low temperatures compared with conventional dc magnetron approaches. More specifically, the effect of the different substrate temperatures and the target bias voltages on the ordering, the microstructure and the magnetic properties of FePt thin films was investigated. Highly ordered FePt thin films were successfully fabricated after post-annealing processes and were patterned into arrays of FePt islands. This patterning process was carried out with e-beam lithography and ion milling. Initial MFM measurements of these islands showed their single-domain structure for all the island sizes, which indicated the high PMA of the FePt. Magnetometry measurements were also carried out with a novel polar magneto-optical Kerr effect (MOKE) system which was designed and built during this project. This system has unique capabilities which are: a) the application of uniform magnetic field up to 2 Tesla, b) the rotation of the field to an arbitrary angle and c) the use of lasers of four different wavelengths. The combination of these abilities enabled measurements on ordered FePt thin films and patterned media which can pave the way for further highly sensitive measurements on magnetic thin films and nanostructures.
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Heldt, Georg. "Arrays of magnetic nanostructures : a dynamical and structural study by means of X-ray experiments." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/arrays-of-magneticnanostructuresa-dynamical-and-structuralstudy-by-means-of-xrayexperiments(99302e83-f625-4c43-99c1-02b2576f0175).html.

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The work in this PhD thesis covers two strands of x-ray experiments: firstly, the characterisation of large arrays of dense structures by means of x-ray scattering, and, secondly, the investigation of hybrid anisotropy square structures with x-ray microscopy. The ability to accurately characterise large arrays of nanoscale magnetic structures is a key requirement for both scientific understanding and technological advance such as bit patterned recording media (BPM). In this work small angle x-ray scattering (SAXS) was investigated as a characterisation technique for large arrays of patterned structures. Dense arrays of magnetic nanostructures were prepared on x-ray transparent membranes and measured. The SAXS data was then modelled to obtain structure parameters such as the mean structure diameter, the diameter distribution and the mean position variance with statistical significance. Arrays (500 x 500 μm2) of nominally uniform nanostructures with centre-to-centre distances between 250 nm-50 nm were structurally characterised and compared to structure diameters obtained by optical scanning electron microscopy measurements. The mean structure diameter was found to be between 39 nm-15nm and agree within the errors with the diameter obtained from SEM measurements. This work provides accurate data on the distribution (variance) of nanostructure sizes which is key for modelling these arrays for applicationin BPM. In the second part of the work, the static and dynamic properties of patterned hybrid anisotropy square structures ([Co/Pd]-Py) were investigated by using time-resolved scanning transmission X-ray microscopy (STXM). In these patterned structures the magnetisation in the layers change both in magnitude and direction and gives rise to interesting new domain configurations. The reciprocal interaction between magnetic vortices in the Py layer and locally circular stripe domains in the Co/Pd was investigated and a mutual domain imprint between the layer was observed. In dynamic excitation experiments the precession of the vortex core is studied and showed good agreement with micromagnetic simulations made by Hrkac and Bryan. As demonstrated patterned hybrid anisotropy square structures have promising magnetic properties with potential applications in data storage (vortex switching) or spintronics (vortex oscillators).
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Esterina, Ria. "Commercialization of bit-patterned media." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54199.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 75-79).
Realm of data storage density has expanded from gigabyte- to terabyte-domain. In such a high areal density, bit-patterned media is a promising candidate to overcome the superparamagnetic limit faced by the conventional continuous media. However, the patterned media concept has not been realized in mass production due to several reasons. Beside the stringent requirement of high-resolution lithography, high production cost is inevitably the major challenging problem. If a low-cost mass fabrication scheme is available, bit-patterned media will be an innovative way in hard disk technology to achieve a storage density beyond 1 Tb/in². The objective of this thesis is to review the patterned media technology and discuss its challenges and commercialization viability. A possible mass-production scheme is discussed. Electron beam lithography and self assembly process of block copolymer are used to fabricate the master template. To ensure high throughput, template replication as well as disk fabrication are carried out by UV-nanoimprint lithography (UV-NIL). Considering the large opportunity of patterned media to enter the market, a business plan was constructed. Enormous profit was proved to be possible when the barrier of technology, intellectual property, and funding can be surpassed. Therefore, patterned media shows to be superior in terms of performance and cost compared to the conventional media.
by Ria Esterina.
M.Eng.
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Talbot, Jennifer. "Write errors in exchange coupled Bit Patterned Media." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/write-errors-in-exchange-coupled-bit-patterned-media(9d44443e-270d-460f-b82e-27f551bf3b47).html.

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The fabrication of Bit Patterned Media has become highly developed, with samples fabricated of over 1.5 Tb/in2. However, writing BPM presents significant challenges and for a system to be developed studies must be made into writing. This work has investigated a number of effects on the writing of Bit Pattterned Media (BPM). Magnetostatic interactions between islands have been used to investigate the effect of patterns of magnetisation on the write-window of a BPM system. A method of acquiring a distribution of patterns was determined and used to vary the probability of a target island switching. This showed that magnetostatic interactions between islands could be modelled as a variation in the anisotropy field. The relationship between island parameter distributions, the write-window and error rates was also explored. The effect of non-Gaussian distributions on the error in a BPM system was studied. It was concluded that tails of island parameter distributions have a significant effect on errors occurring in the write process of a BPM system. Therefore an accurate distribution of island parameters must be known and the necessary accuracy of such a distribution was established. Furthermore a model of BPM writing where the shape of the head field is approximated from the value at the maximum head field gradient will not account for switching in the tail of a real head field. This led onto a study of the ideal write point in BPM. In conventional recording theory the medium is designed to switch when the applied head field is at the position of its maximum gradient, which produces sharp transitions between magnetisation regions. A natural assumption in BPM is that the system could be optimised by setting the island switching field in a similar manner. This strategy of optimisation was investigated to see what gives the minimum error, or maximum write-window. It was concluded that optimisation could not be solely based on the maximum head field gradient, furthermore assuming the shape of the head field from this point will not produce an accurate estimation of the error in a BPM system.
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Aravindakshan, Vibin. "Role of bit patterned media in future of hard disk drives." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42140.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.
Includes bibliographical references (p. 60-61).
The hard disk industry has traditionally stayed competitive by competing on the means of price alone by cutting down aggressively on cost via increase of areal density. Continuing increases in the areal density of hard disk drives will be limited by thermal instability of the thin film medium and is estimated to be limited to about 500Gb/in2. Patterned media, in which data are stored in an array of single.domain magnetic particles, have been suggested as a means to overcome this limitation and to enable recording densities greater than ITb/in2. However, the implementation of patterned media requires fabrication of sub-50-nm features over large areas and the design of recording systems that differ from those used in conventional hard drives. This report discusses the challenges facing patterned media, the fabrication of arrays of ́small magnetic particles and their magnetic properties. The practical implementation of patterned media recording schemes is assessed via technology estimates and cost analysis.
by Vibin Aravindakshan.
M.Eng.
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Shi, Yuanjing. "Investigation of island geometry variations in bit patterned media storage systems." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/investigation-of-island-geometry-variations-in-bit-patterned-media-storage-systems(b16092b6-7260-4dc5-aa30-7dabb2c7a46f).html.

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Bit-Patterned Media (BPM) has been recognised as one of the candidate technologies to achieve an areal density beyond 1Tb/in2 by fabricating single-domain islands out of continuous magnetic media. Though much attention has been focused on the fabrication of BPM, existing lithography techniques demonstrate difficulties in producing uniform islands over large areas cost effectively; the resulting fabricated islands often vary in position and size. The primary purpose of the research documented in this thesis is to investigate the issue of island geometry variations on the data recovery process from a perpendicular patterned media with head and media configurations optimised to achieve an areal density of 1Tb/in2. In order to achieve the research aim, a read channel model has been implemented as a platform to evaluate the read channel performance numerically. It can be also altered to investigate new read channel designs. The simulated results demonstrate that island geometry variations have a detrimental effect on read channel performance. It has shown that a BPM system can be tolerant to island position variations, but more effort needs to be paid to the effect that island size variations have on the read channel performance. A new read channel design revolving around the design of a modified trellis has been proposed for use in the Viterbi detector in order to combat the effect of island geometry variations. The modified trellis for island position variations results in extra states and branches compared to the standard trellis, while the modified trellis for island size variations results in only extra branches. The novel read channel designs demonstrate an improved read channel performance in the presence of island geometry variations even with increasing amounts of island position and size variations. There are two ways to obtain the read channel performance in terms of the bit-error-rate (BER): a) by running a numerical Monte-Carlo simulation to count the number of bits in error at the output of the read channel model and b) using an analytical approach to calculate the BER by approximating the noise into a known distribution. It is shown that both ways demonstrate very similar results, which indicates as long as the distribution of the noise present in read channel model is predictable, the analytical approach can evaluate the BER performance more efficiently, especially when the BER is low. However, the Monte-Carlo simulation is still useful for understanding of the correlation of the errors. Novel trellis proposed in this work will contribute to the commercial development of BPM in two ways: a) to improve the data recovery process in BPM systems, b) to allow a tolerance of 10% size variations for the existing fabrication techniques.
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Alexandrou, Marios. "Magneto-optic Kerr and Hall effect measurements for the characterisation of bit patterned media." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/magnetooptic-kerr-and-hall-effect-measurements-for-the-characterisation-of-bit-patterned-media(fba9cd67-86c0-4382-ad65-52c521f70e5d).html.

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For the past 50 years, the magnetic storage industry has been the ultimate provider, covering the ever-expanding needs of digital mass storage. Up to now, scaling to smaller dimensions has been the core approach for achieving higher areal densities in conventional media. However, recent studies have shown that further miniaturisation is physically bound by superparamagnetic effects. Bit patterned media (BPM) is one of the most promising solutions for extending the areal densities beyond 1Tbit/in². The ability to magnetically characterise novel BPM is a key requirement for its future commercialisation. The work presented in this thesis describes the investigation of the Magneto-Optic Kerr Effect (MOKE) and the Anomalous Hall Effect (AHE) techniques, used in the characterisation of BPM samples. These samples were produced as part of this work using a customised subtractive fabrication process. Continuous thin magnetic films with Ptseed(10nm)/[Co(0.4nm)/Pt(1nm)]x15 composition and perpendicular anisotropy, were deposited using electron-beam (e-beam) evaporation, and subsequently patterned into magnetic nano-islands through means of e-beam lithography and Ar⁺ ion milling. In terms of the MOKE technique, a fully customised polar MOKE system has been developed and successfully used to observe the hysteretic behaviour of magnetic nano-island arrays with varying dimensions. An expected reduction in the MOKE signal due to pattering has been observed, as well as an additional signal reduction due to the scattering effect arising from the non-vertical sidewalls of the dome-shaped islands. In the case of islands with improved shape profile, the magnetic reversal of BPM arrays with islands sizes down to 35nm has been successfully detected, demonstrating a sensitivity of approximately 6x10⁻¹³emu for the MOKE system. In terms of the AHE technique, Au Hall crosses were deposited on top of the BPM arrays that had been previously characterised by MOKE, allowing the direct comparison and cross-verification of the results obtained by the two techniques. A revised Hall cross design, where the Hall crosses were generated by direct patterning of the Pt seed layer, has provided a significant improvement in AHE signal. This has allowed the detection of the magnetic reversal of individual sub-50nm magnetic islands, demonstrating a sensitivity of approximately 6.6x10⁻¹⁵emu for the AHE technique. The spatial sensitivity of these Hall cross structures has been experimentally determined, indicating a decrease in sensitivity with increasing distance from the cross centre and with decreasing island diameter. In conclusion, the sensitivity profile of Hall cross structures must be taken into account for the accurate interpretation of BPM characterisation results obtained by the AHE technique. Finally, some suggestions are outlined with regard to the future improvement of the developed characterisation techniques and the further continuation of the work presented in this thesis.
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Matthes, Patrick. "Magnetic and Magneto-Transport Properties of Hard Magnetic Thin Film Systems." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-192683.

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The present thesis is about the investigation of ferromagnetic thin film systems with respect to exchange coupling, magnetization reversal behavior and effects appearing in magnetic heterostructures, namely the exchange bias and the giant magnetoresistance effect. For this purpose, DC magnetron sputtered thin films and multilayers with perpendicular magnetic anisotropy were prepared on single crystalline and rigid as well as flexible amorphous substrates. The first part concentrates on magnetic data storage applications based on the combination of the concept of bit patterned media and three dimensional magnetic memory, consisting of at least two exchange decoupled ferromagnetic storage layers. Here, [Co/Pt] multilayers, revealing different magnetic anisotropies, have been applied as storage layers and as spacer material Pt and Ru was employed. By the characterization of the magnetization reversal behavior the exchange coupling in dependence of the spacer layer thickness was studied. Furthermore, with regard to the concept of bit patterned media, the layers were also grown on self-assembled silica particles, leading to an exchange decoupled single-domain magnetic dot array, which was studied by magnetic force microscope imaging and angular dependent magneto-optic Kerr effect magnetometry to evaluate the reversal mechanism and its dependence on the array dimensions, mainly the diameter of the silica particles and layer thicknesses. To complete the study, micromagnetic simulations were performed to access smaller dimensions and to investigate the dependence of intralayer as well as interlayer coupling on the magnetization reversal of the dot array with multiple storage layers. The second part focuses on the investigation of the giant magnetoresistance effect in systems with perpendicular magnetic anisotropy, where L10 -chemically ordered FePt alloys and [Co/Pt] as well as [Co/Pd] multilayers were utilized. In case of FePt, where high temperatures during the deposition are necessary to induce the chemical ordering, diffusion and alloying of the spacer material often prevent a sufficient exchange decoupling of the ferromagnetic layers. However, with Ru as spacer material a giant magnetoresistance effect could be achieved. Large improvements of the magnetoresistive behavior of such trilayer structures are presented for [Co/Pt] and [Co/Pd] multilayers, which can be deposited at room temperature not limiting the choice of spacer as well as substrate material. Furthermore, in systems consisting of one ferromagnet with perpendicular magnetic anisotropy and one ferromagnet with in-plane magnetic easy axis, a linear and almost hysteresis-free field dependence of the electrical resistance was observed and the behavior for various thickness series has been intensively studied. Finally, the corrosion resistance in dependence of the capping layer material as well as the magnetoresistance of a strained flexible pseudo-spin-valve structure is presented. In addition, in chapter 2.5.2 an experimental study of an improved crystal growth of FePt at comparable low temperatures by molecular beam epitaxy and further promoted by a surfactant mediated growth using Sb is shown. Auger electron spectroscopy as well as Rutherford backscattering spectrometry were carried out to confirm the surface segregation of Sb and magnetic characterization revealed an increase of magnetic anisotropy in comparison to reference layers without Sb
Die vorliegende Dissertation beschäftigt sich mit der Untersuchung ferromagnetischer Dünnschichtsysteme im Hinblick auf die Austauchkopplung, das Ummagnetisierungsverhalten und Effekte wie z.B. den Exchange Bias Effekt oder den Riesenmagnetwiderstandseffekt (GMR), welche in derartigen Heterostrukturen auftreten können. Die Probenpräparation erfolgte mittels DC Magnetronsputtern, wobei auf einkristallinen aber auch flexiblen sowie starren amorphen Substraten abgeschieden wurde. Im ersten Teil der Arbeit werden Untersuchungen mit dem Hintergrund einer Anwendung als magnetischer Datenträger vorgestellt. Konkret werden hier die Konzepte Bit Patterned Media (BPM) und 3D Speicher miteinander kombiniert. Letzteres Konzept basiert auf der Verwendung wenigstens zweier austauschentkoppelter ferromagnetischer Schichten, für welche [Co/Pt] Multilagen mit unterschiedlicher magnetischer Anisotropie verwendet wurden. Als Zwischenschichtmaterial diente Pt und Ru. Durch die Charakterisierung des Ummagnetisierungsverhaltens wurde die Austauschkopplung in Abhängigkeit der Zwischenschichtdicke untersucht. Darüber hinaus wurden jene Schichtstapel zur Realisierung des BPM-Konzeptes auf selbstangeordnete SiO2 Partikel mit unterschiedlichen Durchmessern aufgebracht, durch welche sich lateral austauschentkoppelte, eindomänige magnetische Nanostrukturen erzeugen lassen. Zur Untersuchung des Ummagnetisierungsverhaltens und der jeweiligen Größenabhängigkeiten (maßgeblich Durchmesser und Schichtdicke) wurden diese mittels Magnetkraftmikroskopie sowie winkelabhängiger magnetooptischer Kerr Effekt Magnetometrie untersucht. Zur weiteren Vertiefung des Verständnisses noch kleinerer Strukturgrößen erfolgten mikromagnetische Simulationen, bei denen die magnetischen Wechselwirkungen lateral (benachbarte 3D Elemente) als auch vertikal (Wechselwirkungen ferromagnetischer Schichten innerhalb eines 3D Elementes) im Interesse standen, sowie deren Auswirkungen auf das Ummagnetisierungsverhalten des gesamten Feldes. Der Fokus des zweiten Teils liegt auf der Untersuchung des Riesenmagnetwiderstandseffektes in Systemen mit senkrechter Sensitivität. Dafür sind ferromagnetische Schichten mit senkrechter magnetischer Anisotropie nötig, wobei hier die chemisch geordnete L10-Phase der FePt Legierung und [Co/Pt] sowie [Co/Pd] Multilagen Anwendung fanden. Für eine chemische Ordnung der FePt Legierung sind hohe Temperaturen während der Schichtabscheidung notwendig, welche eine hinreichende Austauschentkopplung beider ferromagnetischer Schichten meist nicht gewährleisten. Grund dafür sind einsetzende Diffusionsprozesse als auch Legierungsbildungen mit dem Zwischenschichtmaterial. In der vorliegenden Arbeit konnte der GMR Effekt daher ausschließlich mit einer Ru Zwischenschicht in FePt basierten Trilagensystemen nachgewiesen und charakterisiert werden. Enorme Verbesserungen der magnetoresistiven Eigenschaften werden im Anschluss für [Co/Pt] und vor allem [Co/Pd] Multilagen vorgestellt. Diese Schichtsysteme mit senkrechter magnetischer Anisotropie können bei Raumtemperatur präpariert werden und stellen daher keine weiteren Anforderungen an das Zwischenschichtmaterial sowie die verwendeten Substrate. Hier wurden neben Systemen mit ausschließlich senkrechter magnetischer Anisotropie auch Systeme mit gekreuzten magnetischen Anisotropien intensiv untersucht, da diese durch einen linearen und weitgehend hysteresefreien R(H) Verlauf imHinblick auf Sensoranwendungen enorme Vorteile bieten. Letztendlich wurde die Korrosionsbeständigkeit in Abhängigkeit des Deckschichtmaterials als auch die mechanische Belastbarkeit von auf flexiblen Substraten abgeschiedenen GMR-Schichtstapeln untersucht. Zusätzlich wird in Kapitel 2.5.2 eine experimentelle Studie zum Surfactant-gesteuerten Wachstum der FePt Legierung mittels Molekularstrahlepitaxie vorgestellt. Als Surfactant dient Sb, wodurch die Kristallinität bei geringer Depositionstemperatur deutlich verbessert werden konnte. Die Oberflächensegregation von Sb wurde mittels Auger Elektronenspektroskopie und Rutherford Rückstreuspektrometrie verifiziert und die Charakterisierung magnetischer Eigenschaften belegt einen Anstieg der magnetischen Anisotropieenergie im Vergleich zu Referenzproben ohne Sb
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Tsunashima, Shigeru, Satoshi Iwata, Yukihiro Yamauchi, Daiki Oshima, and Takeshi Kato. "Fabrication of L12-CrPt3 Alloy Films Using Rapid Thermal Annealing for Planar Bit Patterned Media." IEEE, 2010. http://hdl.handle.net/2237/14454.

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Bonivel, Joseph T. Jr. "Consumable Process Development for Chemical Mechanical Planarization of Bit Patterned Media for Magnetic Storage Fabrication." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3573.

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As the superparamagnetic limit is reached, the magnetic storage industry looks to circumvent the barrier by implementing patterned media (PM) as a viable means to store and access data. Chemical mechanical polishing (CMP) is a semiconductor fabrication technique used to planarize surfaces and is investigated as a method to ensure that the PM is polished to surface roughness parameters that allow the magnetic read/write head to move seamlessly across the PM. Results from this research have implications in feasibility studies of utilizing CMP as the main planarization technique for PM fabrication. Benchmark data on the output parameters of the CMP process, for bit patterned media (BPM), based on the machine process parameters, pad properties, and slurry characteristics are optimized. The research was conducted in a systematic manner in which the optimized parameters for each phase are utilized in future phases. The optimum results from each of the phases provide an overall optimum characterization for BPM CMP. Results on the CMP machine input parameters indicate that for optimal surface roughness and material removal, low polish pressures and high velocities should be used on the BPM. Pad characteristics were monitored by non destructive technique and results indicate much faster deterioration of all pad characteristics versus polish time of BPM when compared to IC CMP. The optimum pad for PM polishing was the IC 1400 dual layer Suba V pad with a shore hardness of 57, and a k-groove pattern. The final phase of polishing evaluated the slurry polishing properties and novel nanodiamond (ND) slurry was created and benchmarked on BPM. The resulting CMP output parameters were monitored and neither the ND slurry nor the thermally responsive polymer slurry performed better than the commercially available Cabot iCue slurry for MRR or surface roughness. Research results indicate CMP is a feasible planarization technique for PM fabrication, but successful implementation of CMP for planarizing PM must address the high initial start up cost, increase in the number of replacement pads, and increase in polishing time to reach the required surface roughness for magnetic storage devices.
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Book chapters on the topic "Bit Patterned Media (BPM)"

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"Bit Patterned Media." In Encyclopedia of Tribology, 233. Boston, MA: Springer US, 2013. http://dx.doi.org/10.1007/978-0-387-92897-5_100121.

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Kuo, D., S. Xiao, and B. Terris. "Bit Patterned Magnetic Recording Media." In Reference Module in Materials Science and Materials Engineering. Elsevier, 2016. http://dx.doi.org/10.1016/b978-0-12-803581-8.03803-0.

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Terris, B. "Bit Patterned Magnetic Recording Media." In Encyclopedia of Materials: Science and Technology, 1–6. Elsevier, 2011. http://dx.doi.org/10.1016/b978-0-08-043152-9.02278-8.

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Conference papers on the topic "Bit Patterned Media (BPM)"

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Li, Hui, Hao Zheng, Yeoungchin Yoon, and Frank E. Talke. "Air Bearing Simulation for Bit Patterned Media." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71228.

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Patterned media is being considered as a means for achieving a storage density beyond 1Tb/in2 on hard disks by reducing cross talk and overcoming thermal stability problems. In this investigation, the flying characteristics of a femto-type slider over bit patterned media (BPM) is investigated. The discrete bits of the disk are modeled as cylindrical protrusions on the disk surface. The steady-state flying characteristics over BPM at ultra-low head disk spacing is simulated.
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Lille, J., K. Patel, R. Ruiz, T. W. Wu, H. Gao, Lei Wan, G. Zeltzer, E. Dobisz, and T. R. Albrecht. "Imprint lithography template technology for bit patterned media (BPM)." In SPIE Photomask Technology, edited by Wilhelm Maurer and Frank E. Abboud. SPIE, 2011. http://dx.doi.org/10.1117/12.898785.

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Juang, Jia-Yang, and Kuan-Te Lin. "Impact of Touchdown Detection on Bit Patterned Media Robustness." In ASME 2013 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/isps2013-2871.

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Bit patterned media (BPM) is considered as a revolutionary technology to enable further increase of areal density of magnetic recording beyond 1 Tbits/in2 [1]. Implementing BPM technology, however, significantly increases the complexity of the recording process, but also poses tremendous tribological challenges on the head-disk interface (HDI) [2]. One of the major challenges facing BPM is touchdown detection by thermal flying-height control (TFC), in which a minute heater located near the read/write transducers is used to thermally protrude a small portion of the slider into contact with the disk, and the contact is then detected by directly or indirectly measuring the friction, temperature rise or vibration caused by the contact [3]–[7]. Most recording heads rely on touchdown detection to achieve a desired flying height (FH), which approaches sub-1-nm regime for many of today’s commercial drives. As a result sensitive and accurate touchdown detection is of critical importance for a reliable head-disk interface by reducing contact duration and unnecessary interaction between the slider and the disk. However, the impact of touchdown on the mechanical robustness of the media has not been properly studied.
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Mate, C. Mathew, Z. Liu, D. Kercher, O. Ruiz, K. Rubin, A. Bogdanov, J. Lille, T. W. Wu, T. R. Albrecht, and B. Marchon. "Impact of Pattern Media Topography on the Tribology of Head-Disk Interfaces." In ASME 2013 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/isps2013-2820.

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Bit patterned media (BPM) is being pursued by the disk drive industry as a way of extending magnetic recording densities beyond 1 Tbits/in2 [1]. As the patterned topography of an unplanarized BPM disk generates a tribology quite different than smooth, continuous media, it is important to assess how this topography will impact the tribology of head-disk interfaces (HDI). In this paper, we quantify the impact of BPM topography on flying height modulation.
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Song, Wenping, Shimin Yu, Deng Pan, Qingkang Liu, and Longqiu Li. "Molecular Dynamics Simulation of Lubricant Transfer Between Slider and Bit Patterned Disk." In ASME 2017 Conference on Information Storage and Processing Systems collocated with the ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/isps2017-5475.

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A modified coarse-grained, bead-spring model for lubricant transfer from a bit patterned media (BPM) disk to a slider is developed using molecular dynamics (MD). The lubricant transfer at slider/BPM disk interface is compared with that at slider/conventional disk interface. In addition, the effect of lubricant thickness and slider flying height is investigated.
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Xiong, Shaomin, Yuan Wang, Xiang Zhang, and David Bogy. "A Magnetic Rotary Encoder for Patterned Media Lithography." In ASME 2014 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/isps2014-6910.

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Bit patterned media (BPM) is expected to enable the magnetic storage density in hard disk drives (HDDs) beyond 1 Tb/in2. BPM uses isolated magnetic islands to record the data information. However, the large volume fabrication of those patterned media disks at an affordable cost is a challenge for this new technology. A master template is the first step for patterned media fabrication. Using nano-imprint technology, the master template can be replicated to tens of thousands of pattern disks. A rotary electron beam lithography machine or plasmonic nanolithography machine is recommended to assist in the fabrication of the master template. In both systems, a high resolution encoder system for positioning in the rotary lithography machine is necessary. In this paper, a magnetic rotary encoder system is introduced. The encoder system can be operated at several thousand revolution per minute (RPM). The scale pitch is 90 nm which is one to two orders smaller than current optical encoders. The resolution is about 2.8 million counts per revolution (CPR). A flying magnetic head is used to retrieve the readback signal from the magnetic encoders. A field programmable gate array (FPGA) is implemented to finish the high speed signal processing and provide a digital format encoder signal to trigger the lithography machine at a rate of several Mega Hertz.
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Mattayakan, Mutita, Siwakon Sokjabok, and Chanon Warisam. "Simple Soft-Information Developers Based on Parallel Detection Scheme in Bit-Patterned Media Recording (BPMR) Systems." In 2021 36th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC). IEEE, 2021. http://dx.doi.org/10.1109/itc-cscc52171.2021.9501473.

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Pan, Jinwen, Prateek Shah, and Roberto Horowitz. "DSP Implementation of a Direct Adaptive Feedforward Control Algorithm for Rejecting Repeatable Runout in Hard Disk Drives." In ASME 2016 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/isps2016-9615.

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A direct adaptive feedforward control method for tracking repeatable runout (RRO) in bit patterned media recording (BPMR) hard disk drives (HDD) is proposed. The technique estimates the system parameters and the residual RRO simultaneously and constructs a feedforward signal based on a known regressor. An improved version of the proposed algorithm to avoid matrix inversion and reduce computation complexity is given. Results for both MATLAB simulation and digital signal processor (DSP) implementation are provided to verify the effectiveness of the proposed algorithm.
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Bagherieh, Omid, Behrooz Shahsavari, and Roberto Horowitz. "Online Identification of System Uncertainties Using Coprime Factorizations With Application to Hard Disk Drives." In ASME 2015 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/dscc2015-9873.

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In hard disk drive (HDD) magnetic recording bit patterned media (BPM), data are written in predetermined paths. The deviation of these paths from the perfect circle is categorized as repeatable run-out (RRO) which needs to be tracked. An adaptive RRO following algorithm was developed in [1,2] in order to track the RRO. This algorithm uses models of the closed-loop sensitivity transfer functions, from the feedforward injection points to position error signal (PES), to estimate the feedforward control actions that are needed to track the RRO. The phase difference between these models and the actual transfer functions must be less than 90 degrees, in order to guarantee the convergence of the adaptive RRO following algorithm. The dual-stage actuators’ gains and resonance modes are affected by temperature variations, which in turn affect all closed loop sensitivity transfer functions. As a consequence, the 90-degree criteria may be violated unless these transfer functions are periodically updated. In this paper, the coprime factorizations method has been used to factorize and identify the uncertain part of the model instead of identifying the entire transfer function of the model. Experimental results conducted on a hard disk drive equipped with dual-stage actuation, confirm the effectiveness of the proposed estimation algorithm.
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Shahsavari, Behrooz, Ehsan Keikha, Fu Zhang, and Roberto Horowitz. "Repeatable Runout Following in Bit Patterned Media Recording." In ASME 2014 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/isps2014-6946.

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An adaptive feedforward controller design for tracking repeatable runout (RRO) in bit patterned media recording (BMPR) is proposed for single stage hard disk drives (HDD). The technique is based on a modified filtered-x least mean squares (MFX-LMS) algorithm with deterministic periodic input, and a novel variable step size that boosts both the convergence rate and the steady state error. Comprehensive simulations are provided to show the effectiveness of the proposed method.
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