Thèses sur le sujet « Ordinateurs – Mémoires magnétiques – Matériaux »
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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.
Texte intégralThe 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.
Texte intégralSynthetic 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.
Texte intégralThe 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.
Texte intégralMagnetic 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.
Texte intégralSarno, Thomas. « Caractérisation sécuritaire des mémoires magnétiques MRAM ». Thesis, Saint-Etienne, EMSE, 2015. http://www.theses.fr/2015EMSE0796.
Texte intégralMRAM (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.
Texte intégralWith 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.
Texte intégralJe 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.
Texte intégralThe 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.
Texte intégralAfter 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
Alhalabi, Rana. « Conception innovante de circuits logiques et mémoires en technologie CMOS/Magnétique ». Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT103.
Texte intégralAfter many studies in recent decades, emerging non-volatile memory technologies have recently taken off in the semiconductor market. Their main objective is to replace flash and DRAM memories that reach their limits in terms of density, miniaturization, consumption or speed improvement. Among the emerging technologies, the MRAM memory has been identified as a strong candidate to become a leading storage technology for future memory applications. That is why we propose in the first part the design of hybrid CMOS / Magnetic circuits of LUT type (Look Up Table) in STT-MRAM technology (Spin Transfer Torque) aiming to realize a demonstrator. The full custom design from A to Z of innovative LUTs has been implemented. We propose in the second part the design of a full memory in SOT (Spin Orbit Torque) technology, for which a patent has been deposited. Finally, in the last part, this type of memory SOT-MRAM as well as others of type STT-MRAM were integrated in a volatile processor to evaluate the possible interests of these magnetic technologies STT and SOT in this type of circuit
Courtade, Lorène. « Développement, mécanismes de programmation et fiabilité de mémoires non volatiles à commutation de résistance MRAM et OxRRAM ». Phd thesis, Université du Sud Toulon Var, 2009. http://tel.archives-ouvertes.fr/tel-00536904.
Texte intégralCourtade, Lorène. « Développement, mécanismes de programmation et fiabilité de mémoires non volatiles à commutation de résistance MRAM et OxRRAM ». Phd thesis, Toulon, 2009. https://theses.hal.science/tel-00536904/fr/.
Texte intégralMicroelectronics has shown a rapid development due to the improvement of performances and the cost reduction. The memory market is a key domain in this sector. The major stake is to accede to universal memory which will replace all the others, by associating the DRAM density and "unlimited" endurance, the SRAM rapidity and the Flash non volatility. We have focused on the MRAM and OxRRAM technologies, having the advantage of being, like the Flash technology, non volatile and compatible with MOS technology. They should also be, according to the architecture adopted, as rapid as a SRAM, as dense as a DRAM and have an almost unlimited endurance. These technologies are based on concepts in which the discrimination between the two states of the memory point is operated by a resistance change. The first part of this thesis has been dedicated to the MRAM technology and particularly to the reliability of the tunnel oxide integrated in the magnetic junction, basic element of MRAM memory cells. The second part has been centered on the development and the understanding of physical programming mechanisms of OxRRAM memory integrating a NiO binary oxide in the memorization element. A particular stress has been put on the development of a simple technological solution in its manufacturing process and permitting to obtain stacks with electrical performances conforming to specifications. Thus, it is possible to consider the nickel oxide integration in very small-sized dimension structures and to aim at a substantial reduction of the memory cell size
Duguay, Sébastien. « Propriétés de stockage de charges de nanocristaux de germanium incorporés dans des couches de silice par implantation ionique ». Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/DUGUAY_Sebastien_2006.pdf.
Texte intégralOne way to improve current Flash memories is to replace the actual continuous floating gate by an array of nanocrystals discrete charge storage. In this work, silicon dioxide (SiO2) on Si layers with embedded germanium nanocrystals (Ge-ncs) were fabricated using Ge+-implantation and subsequent annealing. Transmission Electron Microscopy (TEM) and Rutherford Backscattering Spectrometry have been used to study the Ge redistribution in the SiO2 films as a function of annealing temperature and implantation conditions (dose, energy). A monolayer of Ge-ncs near and clearly separated of the Si/SiO2 interface was formed under specific annealing and implantation conditions. This layer, with a nc density and mean-size measured to be respectively of the order of 1x1012 /cm2 and 4,5 nm, is located at approximately 4 nm from the Si/SiO2 interface. Increasing the implantation dose leads to the formation of a second monolayer situated in the middle of the SiO2 film. Capacitance-voltage measurements were performed on metal-oxide-semiconductor (MOS) structures containing such implanted SiO2 layers in order to study their electrical properties. The results indicate a strong memory effect at relatively low programming voltages (< 5V), due to the presence of Ge-ncs near the Si/SiO2 interface. Retention and charging times are however found to be incompatible with industrial requirements
Locatelli, Nicolas. « Dynamique par transfert de spin et synchronisation d’oscillateurs couplés à base de vortex magnétiques ». Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112322/document.
Texte intégralMy PhD work is dedicated to the spin transfer induced self-sustained dynamics of two coupled vortices, in nano-pillars spin-valves structures (Py/Cu/Py). A first objective was to understand the spin-polarized transport processes as well as spin transfer mechanisms associated to highly non-homogeneous magnetic configurations. This study allows me to identify and then precisely tune the vortex based magnetic configurations, and notably to observe the influence of spin transfer on reversal mechanisms of the vortex core. Combining analytical calculations and micro-magnetic simulations, we determine the conditions on relative parameters for the two vortices (chiralities and polarities) necessary to obtain self-sustained gyrotropic oscillations of the coupled vortices in a single pillar. A very interesting case is predicted for the pillars with larger diameters (typically over 200nm) for which the critical current is reduced to zero. The experimental results confirm the predictions that a coupled dynamics exists with linewidths as narrow as 200kHz, that is a record at zero field (corresponding to a quality factor Q ≈ 5000, an order of magnitude over the self-sustained oscillations of a single vortex), and even down to 50kHz under external field.A second objective was to investigate the synchronization of two vortex based spin transfer oscillators. We demonstrate theoretically that the phase locking through dipolar coupling of two identical oscillators can be achieved for any parameters of the two vortex. However, the coupling is three times stronger when vortices have opposite core polarities. From an experimental point of view, the synchronization capability for two oscillators having a frequency mismatch reaching up to 10 % of the auto-oscillation frequency has been demonstrated. This work, being part of the research effort made to improve the rf properties of spin transfer nano-oscillators emphasizes how the excitation of coupled magnetizations modes is important to reach lower and lower linewidths
Vincent, Adrien F. « Vers une utilisation synaptique de composants mémoires innovants pour l’électronique neuro-inspirée ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS034/document.
Texte intégralArtificial neural networks, which take some inspiration from the behavior of biological brains and their learning capabilities, are promising tools to address emerging computing uses known as “cognitive” tasks like classifying images or natural language interaction. However, implementing them on conventional computers is poorly efficient. A solution to this problem is to develop specialized acceleration chips which feature:• neurons, the information processing units, which can be implemented efficienctly with current electronic technologies;• synapses, the connections between the neurons which also support the learning process by adjusting their electrical conductance (“synaptic plasticity”). Implementing artificial synapses with high integration and on-line learning capabilities is still a challenge.This thesis explores the use of innovative memory nanodevices as artificial synapses: some of their rich plastic behaviors naturally implement features that are difficult to access with other devices.First, we investigate spin-transfer torque magnetic tunnel junctions, that are currently develop in industry as a new non volatile memory technology. We show that they can also be used as binary artificial synapses. After modeling their intrinsic stochastic behavior analytically, we describe how to harness this behavior to facilitate the implementation of an on-line probabilistic learning rule. With simulations tools developped in the laboratory, we detail the impact of the programming regime on the resilience of a system that uses such synapses, as well as on the system's power consumptionWe then investigate Ag2S electrochemical metalization cells, another type of innovative memory nanodevices fabricated and characterized by collaborators from Université de Lille I, who had already observed the existence of several plastic behaviors. We discovered an additional plasticity, close to a behavior known in neurosciences. With a simple analytical model that allows a better understanding of the relationships between theses plasticities, we show by simulations means a proof of concept of an unsupervised learning that relies on the interaction of the plastic behaviors theses nanodevices feature.Finally, we consider the challenges arising from the circuits that are required to read and write such artificial synapses in a neuro-inspired system.The results of this Ph.D. work pave the way for the design of neuro-inspired systems that can learn by harnessing the rich plastic behaviors that are featured by innovative memory nanodevices
Cabout, Thomas. « Optimisation technologique et caractérisation électrique de mémoires résistives OxRRAM pour applications basse consommation ». Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4778/document.
Texte intégralToday, non-volatile memory market is dominated by charge storage based technologies. However, this technology reaches his scaling limits and solutions to continue miniaturization meet important technological blocks. Thus, to continue scaling for advanced nodes, new non-volatile solutions are developed. Among them, oxide based resistive memories (OxRRAM) are intensively studied. Based on resistance switching of Metal/Isolator/Metal stack, this technology shows promising performances and scaling perspective but isn’t mature and still suffer from a lake of switching mechanism physical understanding.Results presented in this thesis aim to contribute to the development of OxRRAM technology. In a first part, an analysis of different materials constituting RRAM allow us to compare unipolar and bipolar switching modes and select the bipolar one that benefit from lower programming voltage and better performances. Then identified memory stack TiNHfO2Ti have been integrated in 1T1R structure in order to evaluate performances and limitation of this structure. Operating of 1T1R structure have been carefully studied and good endurance and retention performances are demonstrated. Finally, in the last part, thermal activation of switching characteristics have been studied in order to provide some understanding of the underling physical mechanisms. Reset operation is found to be triggered by local temperature while retention performances are dependent of Set temperature
Perrissin, fabert Nicolas. « Miniaturisation extrême de mémoires STT-MRAM : couche de stockage à anisotropie de forme perpendiculaire ». Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT054/document.
Texte intégralMost of the actual STT-MRAM development effort is nowadays focused on out-of-plane magnetized MTJ taking advantage of the perpendicular magnetic anisotropy (PMA) arising at magnetic metal/oxide interface. This interfacial anisotropy allows conciliating large anisotropy required to insure a sufficient retention of the memory together with low switching current density thanks to weak spin-orbit coupling. However this PMA is too weak to insure 10 year retention up to 100°C in sub-20 nm devices. For deeply sub-20 nm nodes, new materials with large bulk PMA and low damping still have to be found. Furthermore, because this PMA is an interfacial effect, it is very sensitive to the structural and chemical properties of the magnetic metal/MgO interfaces contributing to dot to dot variability. To solve these problems in very small feature size STT-MRAM, we propose a totally novel approach: use MTJ stacks in which the storage layer anisotropy is uniquely controlled by its out-of-plane shape anisotropy i.e. by giving the storage layer a cylindrical shape with large enough aspect ratio (thickness / diameter typically > 1). In such structure, for purely magnetostatic reasons, the storage layer magnetization lies out-of-plane. With this approach, the geometry of conventional 2D thin layers is thus replaced by a 3D geometry. This innovative approach had several advantages: (i) it creates a strong and robust source of perpendicular anisotropy, much less sensitive to interfacial defects and thermal fluctuations; (ii) allows the use of well-known materials with mastered growth and low magnetic damping, such as Permalloy in combination with FeCoB at the interface of the MgO tunnel barrier and (iii) yields to an extreme scalability of the memory point, down to the sub-10 nm node, as the same materials can be used at very low nodes
Gourvest, Emmanuel. « Développement et élaboration par MOCVD de matériaux à changement de phase à base d'alliages GeTe : applications aux mémoires embarquées pour la microélectronique ». Phd thesis, Grenoble INPG, 2010. https://theses.hal.science/tel-00668137.
Texte intégralPhase-Change Random Access Memories (PCRAM) are one of the most promising candidates for next generation of nonvolatile memories. However, this technology presents two major drawbacks: an archival life for high operating temperatures too short and power consumption too high. The first objective of this work was to develop new phase change materials by PVD to replace the common Ge2Sb2Te5 unsuitable for embedded applications. The second objective was to develop the targeted material by plasma-assisted MOCVD to assess the feasibility of confined devices requiring low operating currents. The study of binary GeTe material showed higher performance than Ge2Sb2Te5 including an estimated archival life up to ten years at 110°C. The impact of the incorporation of doping elements N and C in GeTe has been under evaluation for development of MOCVD. It has been shown a pronounced increase in thermal stability of doped materials that we explain by the formation of an amorphous phase of nitride or carbide during crystallization. Using a pulsed liquid MOCVD tool with plasma assistance allowed depositing GeTe thin films in crystalline or amorphous phase, with properties of phase transition similar to sputtered GeTe ones
Cargnini, Luís Vitório. « Applications des technologies mémoires MRAM appliquées aux processeurs embarqués ». Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20091/document.
Texte intégralThe Semiconductors Industry with the advent of submicronic manufacturing flows below 45 nm began to face new challenges to keep evolving according with the Moore's Law. Regarding the widespread adoption of embedded systems one major constraint became power consumption of IC. Also, memory technologies like the current standard of integrated memory technology for memory hierarchy, the SRAM, or the FLASH for non-volatile storage have extreme intricate constraints to be able to yield memory arrays at technological nodes below 45nm. One important is up until now Non-Volatile Memory weren't adopted into the memory hierarchy, due to its density and like flash the necessity of multi-voltage operation. These theses has by objective work into these constraints and provide some answers. Into the thesis will be presented methods and results extracted from this methods to corroborate our goal of delineate a roadmap to adopt a new memory technology, non-volatile, low-power, low-leakage, SEU/MEU-resistant, scalable and with similar performance as the current SRAM, physically equivalent to SRAM, or even better with a area density between 4 to 8 times the area of a SRAM cell, without the necessity of multi-voltage domain like FLASH. This memory is the MRAM (Magnetic Memory), according with the ITRS one candidate to replace SRAM in the near future. MRAM instead of storing charge, they store the magnetic orientation provided by the spin-torque orientation of the free-layer alloy in the MTJ (Magnetic Tunnel Junction). Spin is a quantical state of matter, that in some metallic materials can have it orientation or its torque switched applying a polarized current in the sense of the field orientation desired. Once the magnetic field orientation is set, using a sense amplifier, and a current flow through the MTJ, the memory cell element of MRAM, it is possible to measure the orientation given the resistance variation, higher the resistance lower the passing current, the sense will identify a logic zero, lower the resistance the SA will sense a one logic. So the information is not a charge stored, instead it is a magnetic field orientation, reason why it is not affected by SEU or MEU caused due to high energy particles. Also it is not due to voltages variations to change the memory cell content, trapping charges in a floating gate. Regarding the MRAM, this thesis has by objective address the following aspects: MRAM applied to memory Hierarchy: - By describing the current state of the art in MRAM design and use into memory hierarchy; - by providing an overview of a mechanism to mitigate the latency of writing into MRAM at the cache level (Principle to composite memory bank); - By analyzing power characteristics of a system based on MRAM on CACHE L1 and L2, using a dedicated evaluation flow- by proposing a methodology to infer a system power consumption, and performances.- and for last based into the memory banks analysing a Composite Memory Bank, a simple description on how to generate a memory bank, with some compromise in power, but equivalent latency to the SRAM, that keeps similar performance
Bouquin, Paul. « The switching paths of spin transfer torque magnetic random access memories ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST009.
Texte intégralIn spin transfer torque random access memories (STTMRAM), the magnetization of a thin ferromagnetic layer is reversed under the action of a polarized spin current. Along this manuscript we study the switching path that the STTMRAM undergo. First I present the basic theoretical concepts necessary for our forthcoming calculations. Then comes a state of the art of the switching path. The first results I present are micromagnetic simulations of the switching. We study the impact of the diameter of the device on the switching path. From these numerical calculations we predict for devices between 20 and 100 nm at room temperature a switching path composed of a coherent phased followed by a domain wall nucleation and motion. It is the switching path expected in our forthcoming measurements. The domain wall dynamics observed in the micromagnetic simulations present complex Walker oscillations that are not understood from the domain wall models of the state of the art. Therefore, I present a more complete model for the domain wall dynamics within a STTMRAM which takes into account the exact geometry of the system. In this geometry the elasticity terms act as a new effective field called the stretch field. The stretch field plays a key role in the wall dynamics and explains the complex Walker oscillations. The conditions under which these effects can be measured are also predicted by our new model. Our measurements are performed on state-of-the-art STTMRAM based on perpendicular magnetic tunnel junction. The diameter of the devices varies between 26 and 200 nm. We characterize our devices by magnetometry, ferromagnetic resonance and electrical time-resolved measurements of the switching path. The switching path in our time-resolved measurements presents the signatures of an initial coherent phase and of a domain wall motion. This is in agreement with the simulated switching path. The complex Walker oscillations predicted by our models are measured in specific devices with an ultrasoft free layer, but not in our most standard stack. This highlight the interest of our analytical models for understanding the behavior of application-oriented devices
Tillie, Luc. « Etude et optimisation de la stabilité thermique et de la tenue en température de P-STT-MRAM pour des applications industrielles ». Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT133.
Texte intégralWith the amount of data increasing drastically during the last few decades, the need for new technological solutions rose. One of the answers to this problem consists in improving the actual hardware with emerging Non-Volatile Memories (e-NVM). Within these new solutions, the Magnetic Random Access Memory (MRAM) gains a lot of attention from the industrial market. With their supposed unlimited endurance, high speed switching, low voltage operations and high data retention at room temperature, the MRAM, especially the Perpendicular Spin Transfer Torque MRAM (P-STT-MRAM), is seen as one of the best contenders for DRAM, SRAM and embedded Flash replacement. To be used in industrial applications, the P-STT-MRAM has to answer to a large range of requirements in terms of data retention (e.g 10 years) and high operating temperature (more than 200°C). However, as measuring high data retention is not practical, solutions have to be found to extract it fastly. This manuscript will propose and compare different thermal stability factor extraction protocols for P-STTMRAM. The most adapted will be used to model the temperature and size dependence of this factor. Then, the temperature limits of P-STT-MRAM will be characterized and different flavours of storage layers will be match with industrial applications. Finally, the electrical parameters dependence with an external magnetic field will be studied and a linear magnetic sensor based on a P-STT-MRAM device will be proposed
Drouard, Marc. « Etude de l'origine des couples magnétiques induits par le couplage spin orbite dans des structures asymétriques à base de Co/Pt ». Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY057/document.
Texte intégralIn order to reduce power consumption in next generations’ electronic devices, one potentialsolution is to implement non-volatility in memory cells. In this goal, the magnetizationswitching of a ferromagnetic material has been used in a memory concept: the MRAM. Thelatest development of this technology, called SOT-RAM, is based on new phenomena calledSOTs (Spin-Orbit Torques) in order to control magnetization direction. Contrary to precedentgenerations (STT-MRAM), it should achieve a higher operating speed and an enduranceadapted for cache and main memories applications. SOTs is a generic term referring to all theeffects, linked to the spin-orbit interaction, and that enable magnetization reversal. They areyet not perfectly understood.The main objective of this Ph.D. was then to study these SOTs through a quasi-staticexperimental measurement setup based on anomalous and planar Hall effects. Itsimplementation and the associated analysis method, as well as the required theoreticalconsiderations for data interpretation are detailed in this manuscript. It has been highlightedthat magnetization switching in perpendicularly magnetization cobalt-platinum systemscannot be explained by the simple models considered thus far in the literature. As a matter offact it has been evidenced that at least two effects have to be considered in order to explainobserved phenomena. In addition, they present different susceptibility both to a modificationof the crystal structure and to a temperature change
Fievre, Michaël. « Conception et validation technologique de têtes intégrées d’écriture multipistes pour l’enregistrement hélicoïdal sur bande ». Grenoble INPG, 2002. http://www.theses.fr/2002INPG0167.
Texte intégralThe data storage techniques knew an important development due to the success of the multimedia activities. Helical recording on tape, that remains the most economical media, is used for the very important data volumes. The number of read/write heads used by this type of recorders increases to improve the transfer rates. Thus the problem of the relative heads positioning becomes central. The manufacture technology of helical recording heads proposed by Alditech is fully integrated on silicon wafers. It constitutes the departure point of the work presented here. The purpose is to build a double head suppressing the positioning problems of heads thanks to the imported technologies of the microelectronic. The gait that brought to propose the structure of the component is presented here. Next the feasibility of this structure is validated by the study of basic technological steps and the realization of the first demonstrator. Besides the perturbations of the magnetic function of the heads introduced by the “double head” technology as well as the crossfeed phenomena between the heads are studied by numerical simulations
Mraihi, Salmen. « Prise en compte de la variabilité dans l’étude et la conception de circuits de lecture pour mémoires résistives ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS218.
Texte intégralNowadays, Systems on chip (SoCs) conception is becoming more and more complex and demand an ever-increasing amount of memory capacity. This leads to aggressive bit cell technology scaling. Nonvolatile resistive memories (PC-RAM, RRAM, MRAM) are promising technologic alternatives to ensure both high density, low power consumption, low area and low latencies. However, scaling lead to significant memory cell and/or memory periphery variability. This thesis aims to address variability issues in read circuitries of resistive memories and propose solutions for read yield enhancement of these memories. To this end, several sub-studies were achieved: overall review of the existing solutions for read yield enhancement, at both circuit and system level; development of a statistical model evaluating the contributions to read margin of the variability of each component of the resistive memory sensing path; analysis, characterization modelling and optimization of the offset of one particular dynamic sense amplifier for resistive memories; proposal of a sense amplifier architecture that features an optimum signal to offset ratio
Chatterjee, Jyotirmoy. « Optimisation de jonctions tunnel magnétiques pour STT-MRAM et développement d'un nouveau procédé de nanostructuration de ces jonctions ». Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT130/document.
Texte intégralThe first aim of the thesis is to study the feasibility of a new process for nanopatterning of sub-30nm diameter tunnel junctions recently patented by Spintec and LTM and to test the properties of tunnel junctions obtained, from the point of view of magnetic and electrical properties. Particular attention will be paid on the characterization of defects generated at the pillar edges when patterning the tunnel junctions and the impact of these defects on the magnetic and transport properties. Another part of the thesis is focused on improving the magnetic and transport MTJ stacks with higher thermal budget tolerance. As a part of this, new materials (W, etc) were used as cap layer or as a spacer layer in composite free layer of pMTJ stacks. Moreover, different magnetic materials combined with different non-magnetic spacer have been investigated to improve the thermal stability factor of the composite storage layers. Detailed structural characterizations were performed to demonstrate the improvements in magnetic and electrical properties. A new RKKY coupling layer was found which allowed to obtain an extremely thin pMTJ stack by reducing the SAF layer thickness to 3.8nm. Seed lees multilayers with enhanced PMA is necesssary to realize a top-pinned pMTJ stack which is necessary to configure a spin-orbit torque MRAM (SOT-MRAM)stack and double magnetic tunnel junction stacks (DMTJs). A new seed less multilyar with enhanced PMA and subsequently advanced stacks such as conventional-DMTJ, thin-DMT, SOT-MRAM stacks, Multibit memory were realized. Finally, electrical properties patterned memory devices were also studied to correlate with the magnetic properties of thin films
Wrobel, Frédéric. « Elaboration d'une base de données des particules responsables des dysfonctionnements dans les composants électroniques exposés à des flux de protons ou de neutrons. Application au calcul des taux d'erreurs dans les mémoires sram en environnement radiatif naturel ». Montpellier 2, 2002. http://www.theses.fr/2002MON20064.
Texte intégralMahato, Prabir. « Study and development of resistive memories for flexible electronic applications ». Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI134.
Texte intégralThe advent of flexible electronics has brought about rapid research towards sensors, bio implantable and wearable devices for assessment of diseases such as epilepsy, Parkinson’s and heart attacks. Memory devices are major component in any electronic circuits, only secondary to transistors, therefore many research efforts are devoted to the development of flexible memory devices. Conductive Bridge Random Access Memories (CBRAMs) based on creation/dissolution of a metallic filament within a solid electrolyte are of great research interest because of their simple Metal Insulator Metal architecture, low-voltage capabilities, and compatibility with flexible substrates. In this work, instead of a conventional metallic oxide or a chalcogenide layer, a biocompatible polymer - Polyethylene Oxide (PEO) – is employed as the solid electrolyte layer using water as solvent. Memory devices, consisting in Ag/PEO/Pt tri-layer stacks, were fabricated on both silicon and flexible substrates using a heterogeneous process combining physical vapour deposition and spin coating. To aim this, a systematic study on the effect of solution concentration and deposition speed on the PEO thickness is presented. SEM/EDX and AFM measurements were then conducted on devoted “nano-gap” planar structures and have revealed the formation of metallic Ag precipitates together with morphological changes of the polymer layer after resistance switching. The performance of the resistive memory devices is then assessed on silicon and flexible substrates. In particular programming voltage statistics, OFF/ON resistance ratio, endurance cycles and retention tests are performed and the effect of current compliance is analysed. The conduction mechanism in the HRS/LRS is studied on the Ag/PEO/Pt and Pt/PEO/Pt reference devices. Finally, the electrical characterization of devices on flexible substrate is performed under mechanical stress, showing promising results. Polymer-based CBRAM devices are therefore suggested as potential candidates for sustainable development of flexible memory devices
Batista, Pessoa Walter. « Probing chalcogenide films by advanced X-ray metrology for the semiconductor industry ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS330/document.
Texte intégralChalcogenide materials are compounds based on S, Se, and Te elements from group VI of the periodic table. They are receiving an extensive interest not only for applications in resistive memories (PCRAM and CBRAM), photonics and photovoltaics but also in the development of new 2-D materials (e.g. spintronics applications). Chalcogenide materials are already present in the semiconductor roadmaps and it is already replacing flash memories (e.g. phase change material and ovonic threshold switch in new random access memory). For the next technology nodes, chalcogenide properties can be scaled by tuning the chemical composition or by reducing the film thickness. Nonetheless, it also means that their properties become more tightly influenced by the chemical composition, the surface/interface effects and the depth-profile composition. Hence, dedicated metrology protocols must be developed, first to assist the optimization of chalcogenide materials processes in cleanroom environment, then to allow non-destructive process monitoring with industry-driven uncertainties. In this PhD thesis, we developed metrology protocols based on X-ray techniques, dedicated to thin chalcogenides materials and fully compatible with inline monitoring. First, we used quasi in-situ X-ray Photoelectron Spectroscopy (XPS) to characterize the surface of Ge, Sb, Te thin materials and compounds, and to study the composition-dependent evolution of the surface after air break and ageing. The efficiency of in situ capping strategies to protect Te-based and Se-based thin layered materials from ageing was also investigated. Secondly, we demonstrated the ability of improved metrology strategies based on in-line Wavelength Dispersive X-ray Fluorescence (WDXRF) and XPS to accurately quantify the chemical composition of Ge-Sb-Te compounds (from 1 to 200 nm) and ultrathin 2D transition metal dichalcogenides (MoS₂, WS₂). Combined WDXRF/XPS analysis was used to determine refined values of composition-dependent relative sensitivity factors for Te4d, Sb4d and Ge3d that allow for XPS-based metrology of PCRAM materials with mastered accuracy. We pointed the need for in-depth study of the significant matrix effects that alter the ability of WDXRF to quantify Nitrogen in Ge-Sb-Te materials: ion beam analysis was carefully investigated as possible input for WDXRF calibration, and a WDXRF protocol was established for inline monitoring of N-doped Ge-Sb-Te films in a specific process window. Finally, we investigated two ways to non-destructively characterize the in-depth chemical distribution in thin chalcogenide films: we demonstrated that the combination of XRF in grazing incidence geometry (GIXRF) and X-ray reflectometry (XRR) was able to unambiguously reveal small process differences along with process-induced diffusion in 10 nm-thick stackings. We showed that the use of multilayered substrate instead of silicon allowed fine-tuning of the depth-dependent X-ray standing wave field, resulting in improved sensitivity of XRR/GIXRF strategies. We also developed an angle-resolved XPS protocol for the evaluation of the first deposition steps of GeTe and Ge₂Sb₂Te₅ films, revealing the process-dependent elemental distribution as a function of the film growth. Therefore, in this work we not only elaborated advanced metrology protocols for the development of new chalcogenide films but also metrological solutions for the next technology nodes (28 nm and below), since current in-line metrology tools reach their detection limits
Zhang, Boyu. « Propagation des parois de domaines combinant courant polarisé et commutation toute optique ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS096/document.
Texte intégralSince the first observation of ultrafast demagnetization in Ni films arising from a pulsed laser excitation, there has been a strong interest in understanding the interaction between ultrashort laser pulses and magnetization. These studies have led to the discovery of all-optical switching (AOS) of magnetization in a ferrimagnetic film alloy of GdFeCo using femtosecond laser pulses. All-optical switching enables an energy-efficient magnetization reversal of the magnetic material with no external magnetic field, where the direction of the resulting magnetization is given by the right or left circular polarization of the light. The manipulation of magnetization through laser beam has long been restricted to one material, though it turned out to be a more general phenomenon for a variety of ferromagnetic materials, including alloys, multilayers and heterostructures, as well as rare earth free synthetic ferrimagnetic heterostructures. Recently, we have observed the same phenomenon in single ferromagnetic films, thus paving the way for an integration of all-optical writing in spintronic devices. Moreover, in similar materials, like [Co/Pt] or [Co/Ni] with high spin polarization and tunable perpendicular magnetic anisotropy (PMA), efficient current-induced domain wall (DW) motion can be observed in magnetic wires, where spin-orbit torque (SOT) or spin transfer torque (STT) provides a powerful means of manipulating domain walls, which is of great interest for several spintronic applications, such as high-density racetrack memory and magnetic domain wall logic. However, the current density required for domain wall motion is still too high to realize low power devices. This is within this very innovative context that my Ph.D. research has focused on domain wall manipulation in magnetic wires made out of thin film with strong perpendicular magnetic anisotropy combining both spin-polarized current and all-optical switching. Different material structures have been explored, in order to investigate the combined effects of helicity-dependent optical effect and spin-orbit torque or spin transfer torque on domain wall motion in magnetic wires based on these structures. We show that domain wall can remain pinned under one laser circular helicity while depinned by the opposite circular helicity, and the threshold current density can be greatly reduced by using femtosecond laser pulses. Our findings provide novel insights towards the development of low power spintronic-photonic devices
Tirano, Sauveur. « Intégration et caractérisation électrique d'éléments de mémorisation à commutation de résistance de type back-end à base d'oxydes métalliques ». Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4713/document.
Texte intégralThis work is focused on the electrical characterization and physical modeling of emerging OxRRAM memories (Oxide Resistive Random Access Memory) integrating nickel or hafnium oxide. After reaching maturity, this memory concept is likely to replace the Flash technology which is still a standard in the CMOS industry. The main advantages of resistive memories technology is their good compatibility with CMOS processes, a small number of manufacturing steps, a high integration density and their attractive performances in terms of memory operation. The first objective of this thesis is to provide enough informations allowing to orientate the elaboration process of the active nickel oxide layer (thermal oxidation, reactive sputtering) then to compare the performances of the fabricated cells with devices featuring a hafnium oxide layer. The second objective is to understand the physical mechanisms responsible of the device resistance change. A physical model is proposed allowing to apprehend SET and RESET phenomenon in memory devices, subject which is still widely debated in the scientific community. The third objective of this thesis is to evaluate electrical parasitic phenomenon observed in 1R-type memory elements (resistive element without addressing device), in particular the parasitic capacitance appearing during cell programming (writing operation)
Nath, Jayshankar. « Mécanisme des couples spin-orbite dans les systèmes à l'oxyde de platine ». Thesis, Université Grenoble Alpes (ComUE), 2019. https://thares.univ-grenoble-alpes.fr/2019GREAY067.pdf.
Texte intégralThe advent of Big Data, Machine Learning (ML) and 5G has placed a greater emphasis on certain key metrics of memory technology such as power consumption, non-volatility, speed, size, and endurance. Magnetic Random-Access Memories (MRAM) such as Spin Transfer Torque MRAM (STT-MRAM) and Spin-Orbit Torque MRAM (SOT-MRAM) have emerged as key contenders in this market, targeted towards replacing the current Complementary Metal-Oxide-Semiconductor (CMOS) based Static RAMs (SRAM) and Dynamic RAMs (DRAM). SOT-MRAMs rely on spins generated by applying a charge current through a metal with a high Spin-Orbit Coupling (SOC) to switch the magnetic memory bit. These Heavy Metals (HM) being resistive, lead to Ohmic losses during the write process. A vast body of work, both academic and industrial, has been dedicated to finding ways to minimize these losses and thereby enhance the energy efficiency. Moreover, the current that is injected into the device during the write process is controlled by a CMOS switching transistor. The size of this transistor increases with the switching current. Hence, a reduction in this current can also lead to a gain in the bit density of the memory.Various approaches have been adopted to achieve this target by means of enhancing the generation of spins per unit applied current. The earliest approaches involved using transition metals with high SOC, metallic alloys and resistive structural phase of the metal. More recent works have focused on interfacial engineering via ultra-thin insertion layers and spin-sink capping materials. One of the current focus is on using oxidation as a means of enhancing the SOTs. Different groups have studied the effect of oxidation of the HM, the Ferro-Magnet (FM) as well as the capping layer consisting of lighter metals such as copper. Although majority of these works report an increase of SOTs in general, the results and conclusions are not consistent. Differing trends of SOT increase have been reported which in turn have been attributed to varied physical phenomenon. In this work, we study the SOTs generated by oxidizing the platinum layer in a Ta/Cu/Co/Pt multilayer stack.We quantify the SOTs in this system using second harmonic torque measurements and do indeed observe an increase in torques. This is verified with spin-pumping measurements, observing an increase in the damping. In order to determine the origin of this increase, we built an oxidation model of the system based on electrical, magnetic and material characterizations and ab-initio Density Functional Theory (DFT) calculations. This led us to the conclusion that unlike previous works, which exclusively explained the findings based on a completely oxidized HM model, in practice the oxygen near the FM/HM interface gets pumped into the FM layer. This not only oxidizes the FM, but it also leaves the HM metallic near the interface. This model was further supported by measurements and calculations of the symmetric and anti-symmetric exchange, which were found to have a linear relationship. Accounting for these observations, once the quantified SOTs are corrected, we see no observable increase in torques. This leads us to conclude that although on a system level there is an increase of SOTs with platinum oxidation, there is no intrinsic contribution of platinum-oxide on the enhancement of torques. This finding has broad consequences in the design of SOT-MRAM, affecting endurance, power consumption and Tunneling Magneto-Resistance (TMR)
Alvarez-Hérault, Jérémy. « Mémoire magnétique à écriture par courant polarisé en spin assistée thermiquement ». Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENY038.
Texte intégralThis thesis deals with MRAMs, new non volatile memories using spintronics original properties. The goal of this work has mainly been to demonstrate that a new MRAM concept was possible to break through limitations due to previous generations (TA-MRAM and STT-RAM). Their respective advantages have been combinated, that is to say thermal stability for the TA-MRAM and writing without any magnetic field for the STT-RAM. A first demonstration of this new STT-TA-MRAM has been given at the beginning of this study, followed by improvements on the structure with significantly better electrical results. As a consequence, the spin transfer torque switching of the storage layer has been a key point of our investigation. Moreover, an innovative experimental setup has been tested to measure the real time magnetization reversal in order to understand better the writing physics. To finish, the tunnel barrier lifetime has been explored, showing that breakdown is slower than expected for short pulses
Bonjour, Christophe. « Inversion de systèmes linéaires pour la simulation des matériaux ferromagnétiques. Singularités d'une configuration d'aimantation ». Phd thesis, 1990. http://tel.archives-ouvertes.fr/tel-00004975.
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