المؤلفون: Mehonic, Adnan, Ielmini, Daniele, Roy, Kaushik, Mutlu, Onur, Kvatinsky, Shahar, Serrano-Gotarredona, Teresa, Linares-Barranco, Bernabe, Spiga, Sabina, Savelev, Sergey, Balanov, Alexander G, Chawla, Nitin, Desoli, Giuseppe, Malavena, Gerardo, Compagnoni, Christian Monzio, Wang, Zhongrui, Yang, J Joshua, Syed, Ghazi Sarwat, Sebastian, Abu, Mikolajick, Thomas, Noheda, Beatriz, Slesazeck, Stefan, Dieny, Bernard, Tuo-Hung, Hou, Varri, Akhil, Bruckerhoff-Pluckelmann, Frank, Pernice, Wolfram, Zhang, Xixiang, Pazos, Sebastian, Lanza, Mario, Wiefels, Stefan, Dittmann, Regina, Ng, Wing H, Buckwell, Mark, Cox, Horatio RJ, Mannion, Daniel J, Kenyon, Anthony J, Lu, Yingming, Yang, Yuchao, Querlioz, Damien, Hutin, Louis, Vianello, Elisa, Chowdhury, Sayeed Shafayet, Mannocci, Piergiulio, Cai, Yimao, Sun, Zhong, Pedretti, Giacomo, Strachan, John Paul, Strukov, Dmitri, Gallo, Manuel Le, Ambrogio, Stefano, Valov, Ilia, Waser, Rainer

مصطلحات موضوعية: Electrical Engineering and Systems Science - Signal Processing, Computer Science - Hardware Architecture, Electrical Engineering and Systems Science - Systems and Control

الوصف: The roadmap is organized into several thematic sections, outlining current computing challenges, discussing the neuromorphic computing approach, analyzing mature and currently utilized technologies, providing an overview of emerging technologies, addressing material challenges, exploring novel computing concepts, and finally examining the maturity level of emerging technologies while determining the next essential steps for their advancement.
Comment: 90 pages, 22 figures, roadmap, neuromorphic

الوصول الحر: http://arxiv.org/abs/2407.02353Test

المؤلفون: Sarantopoulos, Alexandros, Lange, Kristof, Rivadulla, Francisco, Menzel, Stephan, Dittmann, Regina

مصطلحات موضوعية: Physics - Applied Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science

الوصف: Enhancing the switching speed of oxide-based memristive devices at a low voltage level is crucial for their use as non-volatile memory and their integration into emerging computing paradigms such as neuromorphic computing. Efforts to accelerate the switching speed often result in an energy tradeoff, leading to an increase of the minimum working voltage. In our study, we present an innovative solution: the introduction of a low thermal conductivity layer placed within the active electrode, which impedes the dissipation of heat generated during the switching process. The result is a notable acceleration in the switching speed of the memristive model system SrTiO$_{3}$ by a remarkable factor of 10$^{3}$, while preserving the integrity of the switching layer and the interfaces with the electrodes, rendering it adaptable to various filamentary memristive systems. The incorporation of HfO$_{2}$ or TaO$_{x}$ as heat-blocking layers not only streamlines the fabrication process, but also ensures compatibility with complementary metal-oxide-semiconductor technology.
Comment: 9 pages, 3 figures

الوصول الحر: http://arxiv.org/abs/2402.07603Test

المؤلفون: Weber, Moritz L, Sohn, Yoo Jung, Dittmann, Regina, Waser, Rainer, Menzler, Norbert H, Guillon, Olivier, Lenser, Christian, Nems̆ák, Slavomír, Gunkel, Felix

المصدر: Journal of Materials Chemistry A. 11(33)

مصطلحات موضوعية: Engineering, Materials Engineering, Chemical Sciences, Physical Chemistry, Bioengineering, Nanotechnology, Macromolecular and Materials Chemistry, Interdisciplinary Engineering, Macromolecular and materials chemistry, Chemical engineering, Materials engineering

الوصف: Metal exsolution reactions enable the preparation of metal-oxide nano-composites from oxide parent materials in a single thermal reduction step. In this process, reducible metals are released from the doped oxide and nucleate in the form of finely dispersed, supported nanoparticles. A reversible exsolution and re-dissolution reaction could provide an effective way to regenerate catalysts, where the surface structure and functionality dynamically adapt to the ambient gas environment. However, the reversibility of exsolution reactions is often limited. We investigate reversibility limitations in the niobium and nickel co-doped perovskite SrTi0.95−xNb0.05NixO3−δ with varying Ni doping concentrations between x = 0.005-0.1. Combined morphological, structural and chemical analyses of the material response upon consecutive thermal treatments in reducing and oxidizing environments reveal a non-correlated bulk and surface response of the material upon redox treatment. While the bulk structural changes are mostly reversible, no re-dissolution of the exsolved surface nanoparticles is detected for the investigated time-temperature window (T = 800 °C, t = 5 h for reduction and reoxidation, respectively). Instead, a modification in the nanoparticle distribution and an increased surface wetting of the support by the exsolved metal species are observed upon reoxidation of the nanoparticles.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/3dr657hqTest

المؤلفون: Wysocki, Lena, Ilse, Sven Erik, Yang, Lin, Goering, Eberhard, Gunkel, Felix, Dittmann, Regina, van Loosdrecht, Paul H. M., Lindfors-Vrejoiu, Ionela

مصطلحات موضوعية: Condensed Matter - Materials Science

الوصف: A key element to tailor the properties of magnetic multilayers is the coupling between the individual magnetic layers. In case of skyrmion hosting multilayers, coupling of skyrmions across the magnetic layers is highly desirable. Here the magnetic interlayer coupling was studied in epitaxial all-oxide heterostructures of ferromagnetic perovskite SrRuO$_3$ layers separated by spacers of the strong spin-orbit coupling oxide SrIrO$_3$. This combination of oxide layers is being discussed as a potential candidate system to host N\'{e}el skyrmions. First order reversal curve (FORC) measurements were performed in order to distinguish between magnetic switching processes of the individual layers and to disentangle the signal of soft magnetic impurities from the samples$'$ signal. Additionally, FORC investigations enabled to determine whether the coupling between the magnetic layers is ferromagnetic or antiferromagnetic. The observed interlayer coupling strength was weak for all the heterostructures, with SrIrO$_3$ spacers between 2 monolayers and 12 monolayers thick.
Comment: 22 pages

الوصول الحر: http://arxiv.org/abs/2109.14292Test

المؤلفون: Christensen, Dennis V., Dittmann, Regina, Linares-Barranco, Bernabé, Sebastian, Abu, Gallo, Manuel Le, Redaelli, Andrea, Slesazeck, Stefan, Mikolajick, Thomas, Spiga, Sabina, Menzel, Stephan, Valov, Ilia, Milano, Gianluca, Ricciardi, Carlo, Liang, Shi-Jun, Miao, Feng, Lanza, Mario, Quill, Tyler J., Keene, Scott T., Salleo, Alberto, Grollier, Julie, Marković, Danijela, Mizrahi, Alice, Yao, Peng, Yang, J. Joshua, Indiveri, Giacomo, Strachan, John Paul, Datta, Suman, Vianello, Elisa, Valentian, Alexandre, Feldmann, Johannes, Li, Xuan, Pernice, Wolfram H. P., Bhaskaran, Harish, Furber, Steve, Neftci, Emre, Scherr, Franz, Maass, Wolfgang, Ramaswamy, Srikanth, Tapson, Jonathan, Panda, Priyadarshini, Kim, Youngeun, Tanaka, Gouhei, Thorpe, Simon, Bartolozzi, Chiara, Cleland, Thomas A., Posch, Christoph, Liu, Shih-Chii, Panuccio, Gabriella, Mahmud, Mufti, Mazumder, Arnab Neelim, Hosseini, Morteza, Mohsenin, Tinoosh, Donati, Elisa, Tolu, Silvia, Galeazzi, Roberto, Christensen, Martin Ejsing, Holm, Sune, Ielmini, Daniele, Pryds, N.

المصدر: Neuromorph. Comput. Eng. 2 022501 (2022)

مصطلحات موضوعية: Computer Science - Emerging Technologies, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Materials Science

الوصف: Modern computation based on the von Neumann architecture is today a mature cutting-edge science. In the Von Neumann architecture, processing and memory units are implemented as separate blocks interchanging data intensively and continuously. This data transfer is responsible for a large part of the power consumption. The next generation computer technology is expected to solve problems at the exascale with 1018 calculations each second. Even though these future computers will be incredibly powerful, if they are based on von Neumann type architectures, they will consume between 20 and 30 megawatts of power and will not have intrinsic physically built-in capabilities to learn or deal with complex data as our brain does. These needs can be addressed by neuromorphic computing systems which are inspired by the biological concepts of the human brain. This new generation of computers has the potential to be used for the storage and processing of large amounts of digital information with much lower power consumption than conventional processors. Among their potential future applications, an important niche is moving the control from data centers to edge devices. The aim of this Roadmap is to present a snapshot of the present state of neuromorphic technology and provide an opinion on the challenges and opportunities that the future holds in the major areas of neuromorphic technology, namely materials, devices, neuromorphic circuits, neuromorphic algorithms, applications, and ethics. The Roadmap is a collection of perspectives where leading researchers in the neuromorphic community provide their own view about the current state and the future challenges. We hope that this Roadmap will be a useful resource to readers outside this field, for those who are just entering the field, and for those who are well established in the neuromorphic community. https://doi.org/10.1088/2634-4386/ac4a83Test

الوصول الحر: http://arxiv.org/abs/2105.05956Test

المؤلفون: Schmidt, Niclas, Kaiser, Nico, Vogel, Tobias, Piros, Eszter, Karthäuser, Silvia, Waser, Rainer, Alff, Lambert, Dittmann, Regina

الوصف: HfO₂ is one of the most common memristive materials and it is widely accepted that oxygen vacancies are prerequisite to reduce the forming voltage of the respective memristive devices. Here, a series of six oxygen engineered substoichiometric HfO₂₋ₓ thin films with varying oxygen deficiency is investigated by conductive atomic force microscopy (c‐AFM) and the switching process of substoichiometric films is observed on the nanoscale. X‐ray diffractometry (XRD) exhibits a phase transition from stoichiometric, monoclinic HfO₂ toward oxygen deficient, rhombohedral HfO₁.₇. The conductance of HfO₂₋ₓ is increasing with increasing oxygen deficiency, which is consistent with the increasing prevalence of the highly conductive rhombohedral phase. Simultaneously, c‐AFM reveals significant local conductivity differences between grains and grain boundaries, regardless of the level of oxygen deficiency. Single grains of highly oxygen deficient samples are formed at significant lower voltages. The mean forming voltage is reduced from (7.0 ± 0.6) V for HfO₂ to (1.9 ± 0.8) V for HfO₁.₇. Resistive switching on the nanoscale is established for single grains for the highest deficient thin film samples. The final resistance state is thereby dependent on the initial conductivity of the grains. These studies offer valuable insights into the switching behavior of memristive polycrystalline HfO₂.

وصف الملف: text

العلاقة: https://tuprints.ulb.tu-darmstadt.de/27119/3/AELM_AELM202300693.pdfTest; https://tuprints.ulb.tu-darmstadt.de/27119/5/aelm202300693-sup-0001-suppmat.pdfTest; Schmidt, Niclas; Kaiser, Nico; Vogel, Tobias; Piros, Eszter; Karthäuser, Silvia; Waser, Rainer; Alff, Lambert; Dittmann, Regina (2024)Impact of Non‐Stoichiometric Phases and Grain Boundaries on the Nanoscale Forming and Switching of HfOₓ Thin Films. In: Advanced Electronic Materials, 2024, 10 (4) doi:10.26083/tuprints-00027119 Article, Secondary publication, Publisher's Version

الإتاحة: https://doi.org/10.26083/tuprints-00027119Test
http://tuprints.ulb.tu-darmstadt.de/27119Test/
https://tuprints.ulb.tu-darmstadt.de/27119/3/AELM_AELM202300693.pdfTest
https://tuprints.ulb.tu-darmstadt.de/27119/5/aelm202300693-sup-0001-suppmat.pdfTest

المؤلفون: Hellwig, Johannes, Funck, Carsten, Siegel, Sebastian, Sarantopoulos, Alexandros, Spithouris, Dimitrios, Menzel, Stephan, Dittmann, Regina

المساهمون: Deutsche Forschungsgemeinschaft, Bundesministerium für Bildung und Forschung

المصدر: Advanced Electronic Materials ; ISSN 2199-160X 2199-160X

الوصف: Memristive devices based on the valence change mechanism are highly interesting candidates for data storage and hardware implementation of synapses in neuromorphic circuits. Although long‐term retention is often required for data storage applications, a slight resistance drift of the low resistive state (LRS) is observed even for stable devices. For other devices, the LRS has been observed to decay rapidly to the high resistive state (HRS). These types of devices are of interest for neuromorphic circuits where short‐term plasticity is required. In this work, the LRS relaxation of volatile, crystalline Pt/SrTiO 3 /Nb:SrTiO 3 : devices is investigated in detail, yielding time constants ranging from milliseconds to seconds. The decay is analyzed in terms of the Gibbs free energy gradient for the contribution of oxygen ion migration. A relaxation model based on drift‐diffusion dynamics is presented. The model may serve as a tool for developing guidelines and design rules for future volatile memristive technology based on Schottky barrier mediated electron transport.

الإتاحة: https://doi.org/10.1002/aelm.202400062Test

المؤلفون: Ambaum, Sonja, Allan, Neil L, Dittmann, Regina, Da Souza, Roger

المصدر: Ambaum , S , Allan , N L , Dittmann , R & Da Souza , R 2024 , ' Oxygen Diffusion in Brownmillerite Sr 2 Fe 2 O 5 is Two-Dimensional: Results from a Molecular Dynamics Study ' , Chemistry of Materials , vol. 36 , no. 4 , pp. 2039-2048 .

الوصف: Electrically insulating A(2)B(2)O(5) brownmillerite materials can be transformed through a reversible, topotactic phase transition to conducting ABO(3-delta) perovskite phases. Such systems are of emerging interest for resistive random-access devices. The key process for the phase transition is oxygen diffusion, but to date, experimental or computational studies yielding oxygen diffusion coefficients in brownmillerite materials are rare. In this study, we use molecular dynamics simulations to directly investigate oxygen tracer diffusion in the brownmillerite Sr2Fe2O5 phase and the SrFeO2.5 perovskite phase. Our results for brownmillerite Sr2Fe2O5 go beyond computed diffusion coefficients: They indicate that oxygen vacancies execute two-dimensional diffusion between the equatorial sites of the FeO6 octahedra, and surprisingly, that oxygen interstitials are not confined to the oxygen-vacancy channels (as widely assumed in the literature) but migrate two-dimensionally by interstitial and interstitialcy mechanisms in the FeO4 layers. Comparisons with experimental data are possible for the perovskite phase, and good agreement is found between simulation and experiment for the oxygen-vacancy diffusivity in terms of both absolute magnitude and activation enthalpy.

وصف الملف: application/pdf

العلاقة: https://research-information.bris.ac.uk/en/publications/a3deb405-c7bf-41dc-8685-6ff56c76a6d9Test

الإتاحة: https://hdl.handle.net/1983/a3deb405-c7bf-41dc-8685-6ff56c76a6d9Test
https://research-information.bris.ac.uk/en/publications/a3deb405-c7bf-41dc-8685-6ff56c76a6d9Test
https://research-information.bris.ac.uk/ws/files/401939909/revised.pdfTest

المؤلفون: Wirth, Konstantin G., Goss, Kalle, Heisig, Thomas, Bauerschmidt, Christoph, Hessler, Andreas, Li, Haolong, Waldecker, Lutz, Dittmann, Regina, Taubner, Thomas

المساهمون: Deutsche Forschungsgemeinschaft

المصدر: Advanced Functional Materials ; volume 34, issue 16 ; ISSN 1616-301X 1616-3028

الوصف: Resistive switching devices based on metal oxides are candidates for nonvolatile memory storage. They often rely on the valence change mechanism, the field‐induced movement of donor ions leading to nanoscale conductive paths in filamentary‐type devices. Devices usually consist of a transition metal oxide like Ta 2 O 5 sandwiched between two metal electrodes. Critical parameters of the devices, such as cycle‐to‐cycle variability, R off / R on ratio, and endurance depend on the morphology and composition of the filaments. However, investigating filaments on the nanoscale is cumbersome, and commonly applied techniques such as conductive atomic force or transmission electron microscopy require delaminating the metal top electrode, inhibiting in operando investigations over many switching cycles. Here, the authors use infrared scattering‐type scanning near‐field optical microscopy (s‐SNOM) to investigate resistive switching in Ta 2 O 5 films with a graphene top electrode in operando and reveal individual filaments on the device level. By selecting an appropriate illumination frequency, the authors can trace the evolution of filaments and the joule heating‐induced retraction of the top electrode until device failure. s‐SNOM promises a deeper understanding of resistive switching devices’ microscopic switching behavior and applies to a wide range of resistive switching oxides, such as HfO 2 , SrTiO 3 , and SiO 2 .

الإتاحة: https://doi.org/10.1002/adfm.202312980Test

المؤلفون: Schmidt, Niclas, Kaiser, Nico, Vogel, Tobias, Piros, Eszter, Karthäuser, Silvia, Waser, Rainer, Alff, Lambert, Dittmann, Regina

المساهمون: Deutsche Forschungsgemeinschaft, Electronic Components and Systems for European Leadership, Horizon 2020 Framework Programme, Bundesministerium für Bildung und Forschung

المصدر: Advanced Electronic Materials ; volume 10, issue 4 ; ISSN 2199-160X 2199-160X

الوصف: HfO 2 is one of the most common memristive materials and it is widely accepted that oxygen vacancies are prerequisite to reduce the forming voltage of the respective memristive devices. Here, a series of six oxygen engineered substoichiometric HfO 2 − x thin films with varying oxygen deficiency is investigated by conductive atomic force microscopy (c‐AFM) and the switching process of substoichiometric films is observed on the nanoscale. X‐ray diffractometry (XRD) exhibits a phase transition from stoichiometric, monoclinic HfO 2 toward oxygen deficient, rhombohedral HfO 1.7 . The conductance of HfO 2 − x is increasing with increasing oxygen deficiency, which is consistent with the increasing prevalence of the highly conductive rhombohedral phase. Simultaneously, c‐AFM reveals significant local conductivity differences between grains and grain boundaries, regardless of the level of oxygen deficiency. Single grains of highly oxygen deficient samples are formed at significant lower voltages. The mean forming voltage is reduced from (7.0 ± 0.6) V for HfO 2 to (1.9 ± 0.8) V for HfO 1.7 . Resistive switching on the nanoscale is established for single grains for the highest deficient thin film samples. The final resistance state is thereby dependent on the initial conductivity of the grains. These studies offer valuable insights into the switching behavior of memristive polycrystalline HfO 2 .

الإتاحة: https://doi.org/10.1002/aelm.202300693Test