The Experts below are selected from a list of 32442 Experts worldwide ranked by ideXlab platform
Peter Gutmann - One of the best experts on this subject based on the ideXlab platform.
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data Remanence in semiconductor devices
USENIX Security Symposium, 2001Co-Authors: Peter GutmannAbstract:A paper published in 1996 examined the problems involved in truly deleting data from magnetic storage media and also made a mention of the fact that similar problems affect data held in semiconductor memory. This work extends the brief coverage of this area given in the earlier paper by providing the technical background information necessary to understand Remanence issues in semiconductor devices. Data Remanence problems affect not only obvious areas such as RAM and non-volatile memory cells but can also occur in other areas of the device through hot-carrier effects (which change the characteristics of the semiconductors in the device), electromigration (which physically alter the device itself), and various other effects which are examined alongside the more obvious memory-cell Remanence problems. The paper concludes with some design and device usage guidelines which can be useful in reducing Remanence effects.
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USENIX Security Symposium - Data Remanence in semiconductor devices
2001Co-Authors: Peter GutmannAbstract:A paper published in 1996 examined the problems involved in truly deleting data from magnetic storage media and also made a mention of the fact that similar problems affect data held in semiconductor memory. This work extends the brief coverage of this area given in the earlier paper by providing the technical background information necessary to understand Remanence issues in semiconductor devices. Data Remanence problems affect not only obvious areas such as RAM and non-volatile memory cells but can also occur in other areas of the device through hot-carrier effects (which change the characteristics of the semiconductors in the device), electromigration (which physically alter the device itself), and various other effects which are examined alongside the more obvious memory-cell Remanence problems. The paper concludes with some design and device usage guidelines which can be useful in reducing Remanence effects.
Yuchen Zhou - One of the best experts on this subject based on the ideXlab platform.
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dependence of the pole tip Remanence on the medium magnetization state underneath the trailing shield of a perpendicular write head
Journal of Applied Physics, 2005Co-Authors: Yuchen ZhouAbstract:Understanding the physical mechanisms responsible for the write head pole-tip Remanence is critical for making perpendicular recording a practically viable technology. In this paper, one of these mechanisms is explored in detail by using a contact scanning recording tester. The pole-tip Remanence of unlaminated perpendicular write heads is studied by varying the magnetization states underneath the trailing shield. It is found that the net medium magnetization underneath the trailing shield acts effectively as magnetomotive force in the head-soft underlayer magnetic flux circuit. A clear correlation between the pole-tip Remanence and the medium magnetization state is demonstrated and characterized. The medium magnetization facilitates the head Remanence effectively, resulting in significant erasure after write. The stiffness of the Remanence shows a clear dependence on the current amplitude of the prior writing. The large physical dimension of the trailing shield makes the effect of medium magnetization si...
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perpendicular write head Remanence characterization using a contact scanning recording tester
Journal of Applied Physics, 2005Co-Authors: Yuchen Zhou, Jian-gang Zhu, Yawshing Tang, Lijie GuanAbstract:In this study, an experimental method for characterizing perpendicular write-head pole-tip Remanence using a contact scanning recording tester is presented. The head Remanence is characterized by imaging the written patterns generated by perpendicular write heads on dc-saturated perpendicular media. Write-head footprints are recorded with pulsed unidirectional currents while the head is stationary, followed by scanning the head in various directions at current-off state. Sufficient head remanent field yields written traces during the current-off scan. Projection of traces in multiple scanning directions enables pinpointing of the pole-tip Remanence locations. It is found that the traces written by the remanent field appear only when pulse current amplitudes exceed a certain threshold value. The strength of remanent field also shows a dependence on current pulse polarity. The “stiffness” of the Remanence is characterized by the amplitude of the opposite write current needed to eliminate the remanent field.
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Effect of pole-tip size on perpendicular recording head Remanence
IEEE Transactions on Magnetics, 2005Co-Authors: Yuchen ZhouAbstract:To aid understanding the physical mechanisms responsible for the perpendicular write head remanent field and thereby improve the write head design, we studied the Remanence of single-pole perpendicular recording heads with trailing shield by using a contact scanning recording tester. We used two different pole-tip size heads in the study. We found that the Remanence areas of the heads tested usually locate at the trailing edge corners of the pole tip. We also found that the Remanence areas of both types of heads are also the head field easy-rising areas when the heads are driven by low write currents. Additionally, the current level that leads to Remanence is the same for both types of heads. However, the Remanence of the small pole-tip heads can be demagnetized by a much lower amplitude reverse current than that of the large pole-tip heads.
M Mikhov - One of the best experts on this subject based on the ideXlab platform.
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dependence of the magnetization and Remanence of single domain particles on the second cubic anisotropy constant
Journal of Applied Physics, 2001Co-Authors: J Geshev, Luis Gustavo Pereira, J E Schmidt, M MikhovAbstract:Magnetization and remanent magnetization curves for noninteracting single-domain particles with cubic magnetocrystalline anisotropy have been calculated, taking into account the first two anisotropy constants. The dependencies of the saturation Remanence, coercivity, Remanence coercivity, and δM plots on the anisotropy constants ratio have been discussed. It has been found that the calculated saturation Remanence shows maxima in the vicinity of the spin-reorientation transition points for both negative and positive first cubic anisotropy constants. The remanent magnetization for the case when the face diagonals 〈110〉 are the easiest magnetization orientations has been analytically determined as well. It has been shown that when more than one type of easiest directions coexist, the Remanence of the system can only be obtained numerically because of the history dependence of the remanent magnetization for some particles’ configurations. The predicted Remanence behavior for systems representing spin-reorient...
J.-m. Liu - One of the best experts on this subject based on the ideXlab platform.
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A Monte Carlo approach of Remanence enhancement in Potts spin lattice
Journal of Applied Physics, 2006Co-Authors: H. B. Zuo, M. F. Zhang, J.-m. LiuAbstract:The hysteresis dynamics of a multidomain Potts lattice with nonzero domain wall width is simulated using kinetic Monte Carlo method. The Remanence enhancement effect is investigated in detail taking into account full spin relaxation in the domain walls, whereas outside domain walls only spin reverse event is allowed. Significant enhancement of the Remanence and weakening of the coercivity with increasing domain walls is revealed. While the dependence of the Remanence and coercivity on domain size and domain wall width is established, the hysteresis area is found to be conserved against the two variables. The conservation property of the hysteresis area predicts that no excess energy is required for the spin relaxation inside the domain walls, thus the Remanence enhancement. Finally, the theoretically predicted scaling relation on the Remanence enhancement is confirmed with the present simulation.
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A Monte-Carlo approach of Remanence enhancement effect in ferroelectric Potts lattice
Ferroelectrics, 2001Co-Authors: J.-m. Liu, Guanghan Cao, Xiaolong Liu, Z.g. LiuAbstract:The hysteresis dynamics of a multi-domain Potts lattice with non-zero domain wall width is simulated using kinetic Monte-Carlo method. The Remanence enhancement effect is investigated, taking into account polarization relaxation in domain walls. Significant enhancement of the Remanence and weakening of the coercivity with increasing domain walls are revealed. The hysteresis area is conserved against variation of domain size and wall width, which predicts that no excess energy is required for the polar relaxation in domain walls, thus the Remanence enhancement. The theoretically predicted scaling relation on the Remanence enhancement is confirmed with the present simulation.
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Remanence enhancement of Potts spin lattice: Monte-Carlo simulation
Solid State Communications, 2001Co-Authors: J.-m. Liu, Z.g. Liu, Hlw L. W. Chan, C. L. ChoyAbstract:Abstract A Monte-Carlo simulation based on multi-state spin Potts model is performed to study the Remanence enhancement effect in nano-sized ferromagnetic materials. Our simulation in a two-dimensional lattice reveals that the Remanence enhancement is significantly dependent on the domain size R and the uniaxial anisotropy constant K . In the case of high uniaxial anisotropy, the Remanence enhancement can be linearly scaled with the normalized exchange length d / R as the latter is small. A good consistency between this scaling and the theoretical prediction is presented.
Donald R. Peacor - One of the best experts on this subject based on the ideXlab platform.
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Are magnetite spherules capable of carrying stable magnetizations
Geophysical Research Letters, 1994Co-Authors: Rob Van Der Voo, Donald R. PeacorAbstract:To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Mississippian Leadville limestone, Colorado. Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/Ms < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendritic nets with units ≈ 1 μm wide, (2) platelets with widths of 1 to 3 μm, (3) mosaic surface units with diameters between 2 and 5 μm; each of these surface elements consists of a single crystal, as verified by selected-area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X-ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi-domain in character and are unlikely to carry stable ancient Remanences. The smooth-surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo-single-domain (PSD) or multi-domain (MD) magnetic properties; they may carry ancient Remanences, although we infer that single-domain (SD), non-spherical, submicrometer magnetite is the principal carrier of Remanence in most carbonates.
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Are magnetite spherules capable of magnetizations? carrying stable
1994Co-Authors: Rob Van Der Voo, Donald R. PeacorAbstract:To determine if magnetite spherules extracted from ancient carbonate rocks can carry ancient remanent magnetizations, electron microscope observations and magnetic data have been obtained for more than 100 individual spherules extracted from the Jurassic Twin Creek limestone, Wyoming, and the Mississippian Leadville limestone, Colorado. Two categories of surface textures (smooth and patterned) correlate with different hysteresis parameters. Spherules with patterned surfaces (Group A) have ratios of saturation remanent magnetization to saturation magnetization (Msr/Ms) < 0.1 and ratios of remanent coercive force to coercive force (Hcr/Hc) mostly ) 3. Most spherules with smooth surfaces (Group B) have 0.1 < Msr/M s < 0.3 and Hcr/Hc< 3. The patterned surfaces consist of (1) parallel dendfitic nets with units = 1 gm wide, (2) platelets with widths of 1 to 3 gm, (3) mosaic surface units with diameters between 2 and 5 gm; each of these surface e!9ments consists of a single crystal, as verified by selected-area electron diffraction patterns showing sharp spots, whereas the spherules as a whole show multicrystalline patterns by X-ray diffraction. The Msr/Ms and Hc values of group A increase with decrease in grain size; these Group A magnetite spherules are undoubtedly multi-domain in character and are unlikely to carry stable ancient Remanences. The smooth-surfaced Group B spherules are not very abundant (< 8% of the entire population) and have pseudo-single-domain (PSD) or multi-domain (MD) magnetic properties; they may carry ancient Remanences, although we infer that single-domain (SD), non-spherical, submicrometer magnetite is the principal carrier of Remanence in most carbonates.
