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David A. Thompson

Bio: David A. Thompson is an academic researcher from IBM. The author has contributed to research in topics: Transducer & Suspension (vehicle). The author has an hindex of 23, co-authored 69 publications receiving 2115 citations.


Papers
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Journal ArticleDOI
David A. Thompson1, J. S. Best1
TL;DR: The evolutionary path of magnetic data storage is reviewed and the physical phenomena that will prevent the use of those scaling processes which have served us in the past are examined, finding that the first problem will arise from the storage medium, whose grain size cannot be scaled much below a diameter of ten nanometers without thermal self-erasure.
Abstract: In this paper, we review the evolutionary path of magnetic data storage and examine the physical phenomena that will prevent us from continuing the use of those scaling processes which have served us in the past. It is concluded that the first problem will arise from the storage medium, whose grain size cannot be scaled much below a diameter of ten nanometers without thermal self-erasure. Other problems will involve head-to-disk spacings that approach atomic dimensions, and switching-speed limitations in the head and medium. It is likely that the rate of progress in areal density will decrease substantially as we develop drives with ten to a hundred times current areal densities. Beyond that, the future of magnetic storage technology is unclear. However, there are no alternative technologies which show promise for replacing hard disk storage in the next ten years.

303 citations

Patent
24 Jun 1977
TL;DR: In this article, a pair of layers of a ferromagnetic and an antiferromagnetic material are deposited upon one another and exchange coupled to retain a unidirectional bias in the plane of the material.
Abstract: In thin film magnetic transducers, e.g., inductive or magnetoresistive recording heads, at least a pair of layers of a ferromagnetic material and an antiferromagnetic material are deposited upon one another and exchange coupled to retain a unidirectional bias in the plane of the ferromagnetic material. When multiple pairs of layers are used, they are separated by layers of nonmagnetic material. In some cases, successive pairs of layers of material with unidirectional bias have their directions of bias pointing in opposite directions. The domain walls in the layers of material are minimized by this technique.

213 citations

Journal ArticleDOI
TL;DR: In this article, a new process for obtaining unidirectional anisotropy in 80:20 NiFe films is described and applied to the biasing of a magnetoresistive read head and no Barkhausen noise was observed in its output.
Abstract: A new process for obtaining unidirectional anisotropy in 80:20 NiFe films is described. This process was applied to the biasing of a magnetoresistive (MR) read head and no Barkhausen noise was observed in its output.

175 citations

Patent
01 Nov 1995
TL;DR: A disk drive power manager that compares energy usage with a predetermined profile to select one of several reduced-power operating modes is presented in this paper, where an attenuated average energy usage value is obtained by attenuating the energy usage measures over time and integrating the results.
Abstract: A disk drive power manager that compares energy usage with a predetermined profile to select one of several reduced-power operating modes. An energy usage register is updated at regular intervals according to the energy used during each time interval. An attenuated average energy usage value is obtained by attenuating the energy usage measures over time and integrating the results. The average energy level is compared with several predetermined energy threshold profiles to select a full- or reduced-power operating mode. Operating mode selection automatically adapts to the usage pattern to optimally balance power consumption with operational accessibility.

152 citations

Journal ArticleDOI
E. Grochowski1, David A. Thompson1
TL;DR: In this paper, historical trends and advanced component work are cited as reason for optimism that the current progress in storage areal density will continue smoothly to at least 5 Gigabits per square inch by the year 2000.
Abstract: Historical trends and advanced component work are cited as reason for optimism that the current progress in storage areal density will continue smoothly to at least 5 Gigabits per square inch by the year 2000. >

90 citations


Cited by
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Proceedings ArticleDOI
28 Oct 2007
TL;DR: The provable data possession (PDP) model as discussed by the authors allows a client that has stored data at an untrusted server to verify that the server possesses the original data without retrieving it.
Abstract: We introduce a model for provable data possession (PDP) that allows a client that has stored data at an untrusted server to verify that the server possesses the original data without retrieving it. The model generates probabilistic proofs of possession by sampling random sets of blocks from the server, which drastically reduces I/O costs. The client maintains a constant amount of metadata to verify the proof. The challenge/response protocol transmits a small, constant amount of data, which minimizes network communication. Thus, the PDP model for remote data checking supports large data sets in widely-distributed storage system.We present two provably-secure PDP schemes that are more efficient than previous solutions, even when compared with schemes that achieve weaker guarantees. In particular, the overhead at the server is low (or even constant), as opposed to linear in the size of the data. Experiments using our implementation verify the practicality of PDP and reveal that the performance of PDP is bounded by disk I/O and not by cryptographic computation.

2,238 citations

Posted Content
TL;DR: Ateniese et al. as discussed by the authors introduced the provable data possession (PDP) model, which allows a client that has stored data at an untrusted server to verify that the server possesses the original data without retrieving it.
Abstract: We introduce a model for provable data possession (PDP) that allows a client that has stored data at an untrusted server to verify that the server possesses the original data without retrieving it. The model generates probabilistic proofs of possession by sampling random sets of blocks from the server, which drastically reduces I/O costs. The client maintains a constant amount of metadata to verify the proof. The challenge/response protocol transmits a small, constant amount of data, which minimizes network communication. Thus, the PDP model for remote data checking supports large data sets in widely-distributed storage systems. We present two provably-secure PDP schemes that are more efficient than previous solutions, even when compared with schemes that achieve weaker guarantees. In particular, the overhead at the server is low (or even constant), as opposed to linear in the size of the data. Experiments using our implementation verify the practicality of PDP and reveal that the performance of PDP is bounded by disk I/O and not by cryptographic computation.

2,127 citations

Journal ArticleDOI
29 Sep 2005-Nature
TL;DR: This work presents an autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces that combines ease of fabrication with exquisite control over the shape, composition and mesoscale organization of the surface structures formed.
Abstract: The fabrication methods of the microelectronics industry have been refined to produce ever smaller devices, but will soon reach their fundamental limits. A promising alternative route to even smaller functional systems with nanometre dimensions is the autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces. This approach combines ease of fabrication with exquisite control over the shape, composition and mesoscale organization of the surface structures formed. Once the mechanisms controlling the self-ordering phenomena are fully understood, the self-assembly and growth processes can be steered to create a wide range of surface nanostructures from metallic, semiconducting and molecular materials.

2,013 citations

Journal ArticleDOI
TL;DR: The phenomenology of exchange bias and related effects in nanostructures is reviewed in this paper, where the main applications of exchange biased nanostructure are summarized and the implications of the nanometer dimensions on some of the existing exchange bias theories are briefly discussed.

1,721 citations

Journal ArticleDOI
TL;DR: This Review tries to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.
Abstract: Multiferroic magnetoelectric composite systems such as ferromagnetic-ferroelectric heterostructures have recently attracted an ever-increasing interest and provoked a great number of research activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.

1,642 citations