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End-to-End Modeling of a Volatile TiO2 Memristor for Neuromorphic Circuit Simulation
Authors:
Lukas Endres,
Hannes Töpfer,
Michaela Blum,
Hauke Honig,
Peter Schaaf
Abstract:
Memristors are promising devices for applications such as non-volatile memory, neuromorphic computing, logic circuits, and analog signal processing. The development of such systems requires accurate simulations based on models that reproduce the electrical behavior of real devices under both continuous and pulsed excitation. This work presents the development of a simulation environment for a vola…
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Memristors are promising devices for applications such as non-volatile memory, neuromorphic computing, logic circuits, and analog signal processing. The development of such systems requires accurate simulations based on models that reproduce the electrical behavior of real devices under both continuous and pulsed excitation. This work presents the development of a simulation environment for a volatile TiO2-based memristor. Experimental measurement data are analyzed to verify the memristive behavior of the device and to identify a suitable model. The model parameters are then optimized to match the measured characteristics. The resulting model is implemented in SPICE and validated by comparing simulation results with measurement data. The comparison shows a good agreement between simulation and experiment, demonstrating that the developed model is suitable for reproducing the electrical behavior of the investigated memristor and can be applied in circuit-level simulations, as demonstrated by a leaky integrate-and-fire neuron.
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Submitted 29 July, 2026;
originally announced July 2026.
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Fostering Innovation: Streamlining Magnetocaloric Materials Research by Digitalization
Authors:
Simon Bekemeier,
Moritz Blum,
Luana Caron,
Alisa Chirkova,
Philipp Cimiano,
Basil Ell,
Inga Ennen,
Michael Feige,
Maik Gaerner,
Thomas Hilbig,
Andreas Hütten,
Günter Reiss,
Tapas Samanta,
Sonja Schöning,
Christian Schröder,
Lennart Schwan,
Chris Taake,
Martin Wortmann
Abstract:
Refrigeration based on the magnetocaloric effect (MCE) can contribute to energysaving, environmentally friendly cooling in private households, or industrial application. The cooling is based on the reversible heat release or uptake during a phase-transformation of the materials that can be controlled by a magnetic field. This process could replace conventional compression-based refrigeration, whic…
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Refrigeration based on the magnetocaloric effect (MCE) can contribute to energysaving, environmentally friendly cooling in private households, or industrial application. The cooling is based on the reversible heat release or uptake during a phase-transformation of the materials that can be controlled by a magnetic field. This process could replace conventional compression-based refrigeration, which often relies on environmentally harmful refrigerants. Here we show, how to digitalize the process chain for the synthesis, theoretical and experimental characterization, and prototypical application of magnetocaloric alloy. Different Heusler alloys are examined experimentally as model systems for potential application in magnetic cooling. OTTR templates are used for the acquisition and semantic representation of knowledge in the development of an ontology. The ontology, when combined with unstructured data, can be exploited to train a model that can then be used to predict missing facts, which can help to gain new insights and to generate new hypotheses. Furthermore, tools are developed that automate data acquisition into ontological structures and workflows are implemented that provide an easy-to-use theoretical and experimental evaluation of the MCE from first principles and raw data.
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Submitted 24 November, 2025;
originally announced November 2025.
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Tuning SMSI Kinetics on Pt-loaded TiO$_2$(110) by Choosing the Pressure: A Combined UHV / Near-Ambient Pressure XPS Study
Authors:
Philip Petzoldt,
Moritz Eder,
Sonia Mackewicz,
Monika Blum,
Tim Kratky,
Sebastian Günther,
Martin Tschurl,
Ueli Heiz,
Barbara A. J. Lechner
Abstract:
Pt catalyst particles on reducible oxide supports often change their activity significantly at elevated temperatures due to the strong metal-support interaction (SMSI), which induces the formation of an encapsulation layer around the noble metal particles. However, the impact of oxidizing and reducing treatments at elevated pressures on this encapsulation layer remains controversial, partly due to…
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Pt catalyst particles on reducible oxide supports often change their activity significantly at elevated temperatures due to the strong metal-support interaction (SMSI), which induces the formation of an encapsulation layer around the noble metal particles. However, the impact of oxidizing and reducing treatments at elevated pressures on this encapsulation layer remains controversial, partly due to the 'pressure gap' between surface science studies and applied catalysis. In the present work, we employ synchrotron-based near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to study the effect of O$_2$ and H$_2$ on the SMSI-state of well-defined Pt/TiO$_2$(110) catalysts at pressures of up to 0.1 Torr. By tuning the O$_2$ pressure, we can either selectively oxidize the TiO$_2$ support or both the support and the Pt particles. Catalyzed by metallic Pt, the encapsulating oxide overlayer grows rapidly in 1x10$^{-5}$ Torr O$_2$, but orders of magnitudes less effective at higher O$_2$ pressures, where Pt is in an oxidic state. While the oxidation/reduction of Pt particles is reversible, they remain embedded in the support once encapsulation has occurred.
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Submitted 22 September, 2022;
originally announced September 2022.
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Fluorescence and phosphorescence from individual C$_{60}$ molecules excited by local electron tunneling
Authors:
Elizabeta Ćavar,
Marie-Christine Blüm,
Marina Pivetta,
François Patthey,
Majed Chergui,
Wolf-Dieter Schneider
Abstract:
Using the highly localized current of electrons tunneling through a double barrier Scanning Tunneling Microscope (STM) junction, we excite luminescence from a selected C$_{60}$ molecule in the surface layer of fullerene nanocrystals grown on an ultrathin NaCl film on Au(111). In the observed luminescence fluorescence and phosphorescence spectra, pure electronic as well as vibronically induced tr…
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Using the highly localized current of electrons tunneling through a double barrier Scanning Tunneling Microscope (STM) junction, we excite luminescence from a selected C$_{60}$ molecule in the surface layer of fullerene nanocrystals grown on an ultrathin NaCl film on Au(111). In the observed luminescence fluorescence and phosphorescence spectra, pure electronic as well as vibronically induced transitions of an individual C$_{60}$ molecule are identified, leading to unambiguous chemical recognition on the single-molecular scale.
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Submitted 27 June, 2005;
originally announced June 2005.