Literatura científica selecionada sobre o tema "Ordinateurs – Mémoires magnétiques – Matériaux"
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Teses / dissertações sobre o assunto "Ordinateurs – Mémoires magnétiques – Matériaux"
Gîndulescu, Anca. "Modeling and simulation of hysteric behavior in magnetic and molecular materials and its application to data storage". Versailles-St Quentin en Yvelines, 2012. http://www.theses.fr/2012VERS0034.
Texto completo da fonteThe first part of the thesis focuses on modeling and simulation of the magnetization switching and the influence of noise in ferromagnetic nanostructures. The second part is concerned with the study of 1D and 2D spin crossover compounds, particularly focusing on the relaxation at low temperature and the size effect in nanoparticles. After an overview of magnetic materials and of the main models developed for the theoretical study of the hysteresis behavior, the third chapter provides a description of our results concerning magnetization reversals driven by magnetic fields and spin polarized currents and the modelization and simulation of noise induced phenomenon in complex hysteretic systems. The fourth and the fifth chapter are devoted to the spin crossover compounds and to the description of some models proposed to explain the phenomenon of spin transition. Chapter six provides an overall view of the 1D spin crossover compounds, focusing on the effect of light at low temperature. The last chapter presents some characteristics of 2D spin crossover systems: the size effect and the relaxation dynamics using the Monte Carlo technique with the Arrhenius algorithm
Fache, Thibaud. "Iridium-based synthetic ferrimagnets for spintronics". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0011.
Texto completo da fonteSynthetic ferrimagnets with perpendicular magnetic anisotropy have been studied extensively in the past decades. Their outstanding properties in terms of spintronics, especially concerning the current-induced magnetic domain wall propagation lead us to contemplate them as promising candidates as materials for magnetic racetrack memories. Besides, considering the remarkable properties of iridium concerning the transport and the generation of pure spin currents by means of spin orbit torque, as well as its large RKKY coupling properties, this material seems to be an excellent material as a spacer for synthetic ferrimagnets. In this manuscript, we study magnetic multilayers composed of two magnetic layers of cobalt separated by an iridium spacer. We optimise the growth of these multilayers by choosing the most adequate thicknesses, so as to obtain a model system for racetrack memories applications. Thus, we maximise the antiferromagnetic exchange between the cobalt layers, and the remanence magnetisation. Besides, we study the spin current generation and transport properties of iridium by spin pumping ferromagnetic resonance means. We draw the conclusion that iridium-based synthetic ferrimagnets can be considered as model systems for racetrack memory technology
Guo, Zongxia. "Electrical and optical manipulation of exchange bias". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0204.
Texto completo da fonteThe rapid growth in scale and complexity of neural network architectures in today's machine learning and artificial intelligence applications is creating a significant demand for advanced hardware solutions. The semiconductor industry is actively seeking next-generation storage technologies that can offer improved speed, density, power consumption, and scalability. One such technology that shows great promise for high-performance data storage and processing is magnetoresistive random access memory (MRAM), which stores information in the magnetic state of materials. However, with the continuous requirement of high-density and ultrafast scenarios, antiferromagnet as the basic unit of MRAM shows obvious advantages. Antiferromagnetic materials have negligible macroscopic magnetism, making them highly robust to external magnetic fields. This property also allows for the absence of dipole interactions between adjacent bits, enabling higher-density integration. Additionally, antiferromagnetic materials exhibit high-frequency dynamics up to the terahertz range, theoretically enabling faster write speeds than ferromagnetic devices. However, such fully compensated magnetic moments make the magnetization state of the antiferromagnetic material difficult to manipulate and detect by traditional electrical methods. In this thesis, we demonstrate the antiferromagnetic exchange bias switching in three-terminal magnetic tunnel junctions and achieve electrical detection of antiferromagnetism by the tunnelling magnetoresistance with a ratio over 80%, which is two orders larger than previous methods. This is achieved by imprinting the state of antiferromagnet IrMn on the CoFeB free layer. We further realize current polarity-dependent switching, rather than current orientation-dependent switching of IrMn down to 0.8 ns. We identify two switching mechanisms, the heating mode and the spin-orbit torque driven mode, depending on the current pulse width. The latter case is supported by numerical simulations, which suggest that spin-orbit torque generated by Pt induces the precession of IrMn and exchange coupling at the IrMn/CoFeB interface determines the switching polarity of IrMn. Furthermore, to break the ferromagnetic and electrical write speed limit and further explore the antiferromagnetic switching speed, we experimentally realize exchange bias switching by a single femtosecond laser pulse. In the IrMn/CoGd structure, the perpendicular exchange bias is investigated for different IrMn thicknesses and CoGd concentrations. Using the optimized structure, the exchange bias was switched under a single femtosecond laser, and the dependence of the exchange bias variations with different laser fluence and pulse numbers was detailed investigated. The pump-probe time-resolved measurement is used to demonstrate the exchange bias switching time scale of less than 100 ps. The grain structure of polycrystalline IrMn films and the amorphous state of CoGd alloy layers are accurately described using atomistic simulations. The IrMn exhibits a faster demagnetization than ferromagnetic materials and each IrMn grain remagnetizing to a single-domain state in only 2 ps. In addition, the different grains of IrMn exhibit independent and stochastic probabilistic switching in the ultrafast time scale. The electrical and all-optical manipulation of exchange bias system allows ultrafast, field-free and energy-efficient control of antiferromagnet with high ordering temperature and thermal stability, making it highly suited to applications
Ouattara, Frédéric. "Primitives de sécurité à base de mémoires magnétiques". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS072.
Texto completo da fonteMagnetic memories (MRAM) are one of the emerging non-volatile memory technologies that have experienced rapid development over the past decade. One of the advantages of this technology lies in the varied fields of application in which it can be used. In addition to its primary function of storing information, MRAM is nowadays used in applications such as sensors, RF receivers and hardware security. In this thesis, we are interested in the use of MRAMs in the design of elementary hardware security primitives. Initially, an exploration in the design of TRNG (True Random Number Generator) based on STT-MRAM (Spin Transfert Torque MRAM) type memories was carried out with the aim of producing a demonstrator and proving its effectiveness for secure applications. Random extraction methods in STT and TAS (Thermally Assisted Switching) memories are presented. We have thus evaluated these magnetic memories within the framework of TRNGs but also for the generation of PUFs (Physically Unclonable Functions) on physical devices
Deleruyelle, Damien. "Etude de dispositifs MTJ (Multiple Tunnel Junctions) et intégration de matériaux high-K pour les mémoires flash à haute densité d'intégration". Aix-Marseille 1, 2004. http://www.theses.fr/2004AIX11036.
Texto completo da fonteSarno, Thomas. "Caractérisation sécuritaire des mémoires magnétiques MRAM". Thesis, Saint-Etienne, EMSE, 2015. http://www.theses.fr/2015EMSE0796.
Texto completo da fonteMRAM (magnetoresistive RAM) is an emergent non-volatile memory technology; it has the particularity to store data in magnetic moments orientations. It has very interesting characteristics that overwhelm mature technologies on several points. Crocus Technology is developing a new MRAM technology called TAS-MRAM (for Thermally Assisted Switching). During write operations, this new MRAM technology uses a current to heat the memory cell. This reduces the power consumption and makes scalability easier. TAS-MRAM are developed for secure or critical applications but this technology relies on spintronic, a field of physics not much studied for electronics security.This work aims to evaluate potential security weaknesses of this technology. More specifically the memory capacity to guarantee data confidentiality was studied. This work was divided in two parts; one part is dedicated to the analysis of MRAM resistance against physical perturbations, with a special focus on magnetic fields (both static and pulsed) effects on read and write operations as well as their effects on data retention. Various methods to reduce these effects were tested and compared. The effect of high temperature was also studied.The second part focuses on the analysis of electromagnetic emissions of the MRAM components during its operations. Methods to retrieve the Hamming weight of data written in the memory are exposed and compared
Fagot, Jean-Jacques. "Développement de nouvelles architectures de sélecteurs pour mémoires non-volatiles embarquées dans des plateformes technologiques avancées 28nm". Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0608.
Texto completo da fonteWith the miniaturization of components and technologies ever more aggressive in terms of dimensions, flash memory face increasingly complex integration problems, generating high costs, especially in 28nm FD-SOI and beyond. The non-volatile integrated memory market is therefore moving towards innovative solutions in full development, more attractive in terms of costs and offering a large margin of evolution. We find, in particular, magnetic (MRAM), resistive (RRAM) and phase change (PCM) memories. However, the competitiveness of these memories being directly related to their size and cost, one of the major challenges is the integration of a selector at the same time compact, performing and inexpensive. The company STMicroelectronics, partner of this thesis, chose to move towards PCM type memories. The selectors are critical components in the operation of this type of memory. In this context, the work of this thesis revolves around three types of selectors for PCM memories: the MOS transistor, the diode, and the bipolar transistor. Each of these selectors has its advantages and disadvantages. The operation and integration in 28nm FD-SOI technology of these selectors is studied, developed, then characterized, and finally, potential improvement axes are proposed in each part
Nicolle, Elsa. "Caractérisations et fiabilité de mémoires magnétiques à accès aléatoires (MRAM)". Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00279958.
Texto completo da fonteJe décris tout d'abord en détail les principes physiques à la base du fonctionnement aussi bien électrique que magnétique des jonctions tunnels magnétiques qui sont au cœur des mémoires magnétiques. Je me suis attachée à chaque étape à identifier les nouveaux facteurs susceptibles d'intervenir dans la fiabilité (par rapport à un processus CMOS classique), en essayant de donner une évaluation quantitative de leur impact éventuel.
Sur cette base, j'ai essayé d'établir et de tester un procédé de caractérisation d'un effet critique de la MRAM : la non-volatilité, qui puisse ensuite être utilisé sur des éléments isolés d'un wafer comme point de vérification de la qualité magnétique du circuit. Nous avons choisi de comparer des calculs de barrière d'énergie à une mesure réelle de la barrière sur des échantillons élaborés dans le cadre de l'Alliance Crolles 2.
Enfin, j'ai mené une étude sur un autre type de structure de mémoires magnétiques faisant intervenir un déplacement de parois magnétiques à l'aide d'un courant. Cette étude visait à estimer, une fois encore, la barrière énergétique de ces nouvelles structures. Nous avons essayé de démontrer qu'elles seraient une perspective intéressante pour la miniaturisation des mémoires magnétiques.
Conraux, Yann. "Préparation et caractérisation d’un alliage amorphe ferrimagnétique de GdCo entrant dans la conception de jonctions tunnel magnétiques : résistance des jonctions tunnel magnétiques aux rayonnements ionisants". Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10148.
Texto completo da fonteThe magnetic random access memories (MRAM) are on the way to supplant the other forms of random access memories using the states of electric charge, and this thanks to their many technical advantages: not-volatility, speed, low consumption power, robustness. Also, the MRAM are alleged insensitive with the ionizing radiations, which was not checked in experiments until now. The current architecture of the MRAM is based on the use of magnetic tunnel junctions (MTJ). These MRAM can present an important disadvantage, because they are likely of present errors of addressing, in particular when integration (density of memory cells) is increasingly thorough. The work undertaken during this thesis relates to these two points: - to check the functional reliability of the MRAM containing JTM exposed to high energy ionizing radiations ; - to study a ferrimagnetic amorphous alloy, GdCo, likely to enter the composition of JTM and allowing to free from the possible errors of addressing by a process of thermal inhibition of the memory cells. This work of thesis showed that the MRAM containing JTM preserve their functional properties fully when they are subjected to intense ionizing radiations, and that GdCo is a very interesting material from the point of view of the solid state physics and magnetism, that its physical properties are very promising as for its applications, and that its integration in a JTM still claims technological developments
Iovan, Adrian. "Elaboration et caractérisation de jonctions tunnel à plusieurs barrières pour l'intégration dans une nouvelle génération de mémoires magnétiques". Université Louis Pasteur (Strasbourg) (1971-2008), 2004. https://publication-theses.unistra.fr/public/theses_doctorat/2004/IOVAN_Adrian_2004.pdf.
Texto completo da fonteAfter discovery of a great tunnel magnetoresistance (TMR) in magnetic tunnel junctions (MTJ) at room temperature, several potential applications based on polarized transport have emerged. Large TMR values at room temperature are very promising, in particular, for the use of the tunnel junctions within magnetic random access memory (MRAM) devices. However, the MRAM currently proposed, which incorporate magnetic junctions tunnel, require to add a semiconductor switch (a CMOS transistor or a PN diode) in series with the cell memory (MTJ). Indeed, in a matrix of MTJ, it is necessary to remove (or block) the stray currents coming from the other elements during the reading of the magnetic state of a given element. However, this process is penalized by the technological difficulty to combine a semiconductor part, where conduction is done in a planar geometry, and a metal/oxide part. One of the means of circumventing this difficulty of integration is to introduce a diode based on metal/insolator multilayers. In this case, diodes can be manufactured with the same size as the magnetic junctions that will lead to an increase of the storage density in the MRAM. In this thesis, we have elaborated such structures and have validated the operating mode of a Metal-Insulator Diode (MID) with a high rectification ratio. The second part of this work is devoted to the integration of the diode thus obtained with a magnetic junction giving the magnetoresitif signal in a MID-RAM structure. This corresponds to contacting the MID diode (blocking function) in series with a magnetic tunnel junction (memory function RAM). The operating mode of the MID-RAM has been validated using simulations and macroscopic contacts between a MID and a magnetic junction. An integrated structure has been realised exhibiting simultaneously TMR signal and rectified current. However, we show that this integration comes up against difficulties related to intrinsic properties of the transport in such structures
Livros sobre o assunto "Ordinateurs – Mémoires magnétiques – Matériaux"
Y, Sakurai, ed. Recent magnetics for electronics. Tokyo: OHMSHA and North-Holland, 1986.
Encontre o texto completo da fonteVoss, Andreas. Installez un disque dur. Paris: Micro Application, 1998.
Encontre o texto completo da fonteTang, Denny D. Magnetic memory: Fundamentals and technology. New York: Cambridge University Press, 2010.
Encontre o texto completo da fonte1976-, Chen Yiran, ed. Nonvolatile memory design: Magnetic, resistive, and phase change. Boca Raton, FL: Taylor & Francis, 2012.
Encontre o texto completo da fonteSakurai, Y. Recent Magnetics for Electronics, 1985/1986 (Japan Annual Reviews in Electronics, Computers and Telecommunications, Vol 21). Elsevier Science Ltd, 1987.
Encontre o texto completo da fonteTang, Denny D., e Yuan-Jen Lee. Magnetic Memory: Fundamentals and Technology. Cambridge University Press, 2010.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Ordinateurs – Mémoires magnétiques – Matériaux"
JAMET, Matthieu, Diogo C. VAZ, Juan F. SIERRA, Josef SVĚTLÍK, Sergio O. VALENZUELA, Bruno DLUBAK, Pierre SENEOR, Frédéric BONELL e Thomas GUILLET. "La spintronique bidimensionnelle". In Au-delà du CMOS, 155–213. ISTE Group, 2024. http://dx.doi.org/10.51926/iste.9127.ch5.
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