arXiv subjects

Stavros G. Stavrinides

Publications and source records attributed to Stavros G. Stavrinides.

4 recordsLinked to original sources

arXiv2026

Criticality in memristor devices and the creation of deep memory

In the present work we describe a way to assess memory capability of real devices, while proposing to the engineering community what to pursue to create devices with deep associated memory capability. The study of the signal produced by a real memristor nano-device focused on the description in terms of the Landau ϕ4 theory for the critical phenomena in finite systems. This further allowed the utilization of the property of the anomalous enhancement of the autocorrelation function when a system is on the Spontaneous Symmetry Breaking (SSB), for improving the quantity of the demonstrated memory, while simultaneously maintaining a very good quality, as this is expressed by the stability of the autocorrelation function. In this proof-of-concept case, the morphology of the signal allowed us to impose the appropriate modifications on the signal so that we finally show how to get very close to the characteristics of the SSB and thus achieve our goal to get as close as possible to the ideal behavior of a Memristor that yields deep memory. Finally, we provide proof of the stability of memristor's operation by showing that solitons "follow" as a skeleton structure the experimentally derived time series.

nlin.CD↗

arXiv2024

Variability in Resistive Memories

Resistive memories are outstanding electron devices that have displayed a large potential in a plethora of applications such as nonvolatile data storage, neuromorphic computing, hardware cryptography, etc. Their fabrication control and performance have been notably improved in the last few years to cope with the requirements of massive industrial production. However, the most important hurdle to progress in their development is the so-called cycle-to-cycle variability, which is inherently rooted in the resistive switching mechanism behind the operational principle of these devices. In order to achieve the whole picture, variability must be assessed from different viewpoints going from the experimental characterization to the adequation of modeling and simulation techniques. Herein, special emphasis is put on the modeling part because the accurate representation of the phenomenon is critical for circuit designers. In this respect, a number of approaches are used to the date: stochastic, behavioral, mesoscopic..., each of them covering particular aspects of the electron and ion transport mechanisms occurring within the switching material. These subjects are dealt with in this review, with the aim of presenting the most recent advancements in the treatment of variability in resistive memories.

physics.app-ph↗

arXiv2023

Real-World Chaos-Based Cryptography Using Synchronised Chua Chaotic Circuits

This work presents the hardware demonstrator of a secure encryption system based on synchronised Chua chaotic circuits. In particular, the presented encryption system comprises two Chua circuits that are synchronised using a dedicated bidirectional synchronisation line. One of them forms part of the transmitter, while the other of the receiver. Both circuits are tuned to operate in a chaotic mode. The output (chaotic) signal of the first circuit (transmitter) is digitised and then combined with the message to be encrypted, through an XOR gate. The second Chua circuit (receiver) is used for the decryption; the output chaotic signal of this circuit is similarly digitised and combined with the encrypted message to retrieve the original message. Our hardware demonstrator proves that this method can be used in order to provide extremely lightweight real-world, chaos-based cryptographic solutions.

cs.CR↗

arXiv2021

Modeling the dynamical behavior of memristive {NiTi} alloy at constant stress for time-varying electric current input signals

The dynamical electric behavior of a NiTi smart alloy thin filament when driven by time varying current pulses is studied by a structure-based phenomenological model that includes rate-based effects. The simulation model relates the alloy's electrical resistivity to the relative proportions of the three main structural phases namely Martensite, Austenite and R-phase, experimentally known to exist in NiTi alloy lattice structure. The relative proportions of the phases depend on temperature and applied stress. Temperature varies due to the self-heating of the filament by the Joule effect when a current pulse passes and also due to convective/radiative interchange with the ambient. The temperature variation with time causes structural phase transitions, which result in abrupt changes in the sample resistivity as the proportions of each lattice phase vary. The model is described by a system of four 1st-order nonlinear differential-algebraic equations yielding the temporal evolution of resistivity and output voltage across the filament for any given time-varying input current pulse. The model corresponds to a 4th-order extended memristor, described by four state variables, which are the proportions of each of the three NiTi lattice phases and temperature. Simulations are experimentally verified by comparing to measurements obtained for samples self-heated by triangular current input waveforms as well as for passively samples with no current input. Numerical results reproduce very well measurements of resistance vs. temperature at equilibrium as well as the full dynamics of experimentally observed I-V characteristic curves and resistance vs. driving current for time-varying current input waveforms of a wide range of frequencies (0.01-10~Hz).

cond-mat.mtrl-sci↗