Journal of Statistical Mechanics: Theory and Experiment, Dec 27, 2019
Resistive switching (RS) is studied in a memristor based on a ZrO2(Y)/Ta2O5 stack under a white G... more Resistive switching (RS) is studied in a memristor based on a ZrO2(Y)/Ta2O5 stack under a white Gaussian noise voltage signal. We have found that the memristor switches between the low resistance state and the high resistance state in a random telegraphic signal (RTS) mode. The effective potential profile of the memristor shows from two to three local minima and depends on the input noise parameters and the memristor operation. These observations indicate the multiplicative character of the noise on the dynamical behavior of the memristor, that is the noise perceived by the memristor depends on the state of the system and its electrical properties are influenced by the noise signal. The detected effects manifest the fundamental intrinsic properties of the memristor as a multistable nonlinear system
ABSTRACT We investigate an overdamped Brownian particle moving in: (a) a dichotomously fluctuatin... more ABSTRACT We investigate an overdamped Brownian particle moving in: (a) a dichotomously fluctuating metastable potential; (b) a random fluctuating periodic potential. For piece-wise linear potential we obtain for case (a) the exact average lifetime and the mean first passage time as a function of the potential parameters, the noise intensity and the mean frequency of switchings of the dichotomous noise. We find noise enhanced stability (NES) in the system investigated. The parameter regions of the fluctuating potential where NES effect can be observed are analytically derived. For case (b) we consider a symmetric periodic potential modulated by white noise. We obtain for such a potential the same relationship between effective diffusion coefficient of Brownian particles and the mean first-passage time, discovered previously for fixed periodic potential (see ref. 3). The phenomenon of diffusion acceleration in comparison with free particle case has been found for arbitrary potential profile. The effective diffusion coefficients for sawtooth, sinusoidal and piecewise parabolic potentials are calculated in closed analytical form.
We show that the increment of generalized Wiener process (random process with stationary and inde... more We show that the increment of generalized Wiener process (random process with stationary and independent increments) has the properties of a random value with infinitely divisible distribution. This enables us to write the characteristic function of increments and then to ...
Abstract The structure of the electron current through an individual filament of a nanometer-size... more Abstract The structure of the electron current through an individual filament of a nanometer-sized virtual memristor consisting of a contact of a conductive atomic force microscope probe to an yttria stabilized zirconia (YSZ) thin film deposited on a conductive substrate is investigated. Usually, such investigation is performed by the analysis of the waveform of this current with the aim to extract the random telegraph noise (RTN). Here, we suggest a new indirect method, which is based on the measurement of the spectrum of the low-frequency flicker noise in this current without extracting the RTN, taking into account the geometrical parameters of the filament. We propose that the flicker noise is caused by the motion (drift/diffusion) of oxygen ions via oxygen vacancies within and around the filament. This allows us to estimate the root mean square magnitude i0 of the current jumps, which are caused by random jumps of oxygen ions, and the number M of these ions. This is fundamental for understanding the elementary mechanisms of electron current flowing through the filament and resistive switching in YSZ–based memristor devices.
Journal of Statistical Mechanics: Theory and Experiment, Sep 2, 2019
We theoretically investigate the fluctuations in the number of emergent magnetic monopoles in spi... more We theoretically investigate the fluctuations in the number of emergent magnetic monopoles in spin ice. The Langevin equation for these fluctuations is deduced. That allows us to calculate the spectrum of relative fluctuations, which can be measured experimentally. Keywords—magnetic monopoles; spin ice; fluctuations; ice rules; generation-recombination.
The results of the experimental investigation of the relationship between the low-frequency noise... more The results of the experimental investigation of the relationship between the low-frequency noise spectrum of the electric current through conducting filaments in Si3N4 films with a thickness of 6 nm on n ++-Si(001) conducting substrates and retention characteristics of these filaments are reported. Two structures are investigated: Si3N4/Si, thin (about 6 nm) Si3N4 film on the n++-Si substrate; Si3N4/SiO2/Si, a similar structure with a 2 nm SiO2 sublayer between the film and the substrate. A detailed comparison of the experimentally extracted parameters, such as average current through the filament, probability density function, and spectrum, is presented with a discussion of possible physical reasons for the difference between the testing structures and their effect on retention characteristics.
Resistive memories are outstanding electron devices that have displayed a large potential in a pl... more 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: stochast...
Here we summarize some relevant results related to nonequilibrium phenomena in mesoscopic and qua... more Here we summarize some relevant results related to nonequilibrium phenomena in mesoscopic and quantum systems. A common phenomenon in the dynamics of out-of-equilibrium systems is the metastability, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. Metastability (see Fig. 1) is a signature of a first order phase transition, often characterized by a long-living metastable state. In particular, the stability of a metastable state can be enhanced by Gaussian and non-Gaussian noise sources. This counterintuitive effect has been found in different physical areas, ranging from spintronics, aggregation kinetics of Brownian particles, Josephson junction systems, to interdisciplinary physical models
Journal of Statistical Mechanics: Theory and Experiment, Dec 27, 2019
Resistive switching (RS) is studied in a memristor based on a ZrO2(Y)/Ta2O5 stack under a white G... more Resistive switching (RS) is studied in a memristor based on a ZrO2(Y)/Ta2O5 stack under a white Gaussian noise voltage signal. We have found that the memristor switches between the low resistance state and the high resistance state in a random telegraphic signal (RTS) mode. The effective potential profile of the memristor shows from two to three local minima and depends on the input noise parameters and the memristor operation. These observations indicate the multiplicative character of the noise on the dynamical behavior of the memristor, that is the noise perceived by the memristor depends on the state of the system and its electrical properties are influenced by the noise signal. The detected effects manifest the fundamental intrinsic properties of the memristor as a multistable nonlinear system
ABSTRACT We investigate an overdamped Brownian particle moving in: (a) a dichotomously fluctuatin... more ABSTRACT We investigate an overdamped Brownian particle moving in: (a) a dichotomously fluctuating metastable potential; (b) a random fluctuating periodic potential. For piece-wise linear potential we obtain for case (a) the exact average lifetime and the mean first passage time as a function of the potential parameters, the noise intensity and the mean frequency of switchings of the dichotomous noise. We find noise enhanced stability (NES) in the system investigated. The parameter regions of the fluctuating potential where NES effect can be observed are analytically derived. For case (b) we consider a symmetric periodic potential modulated by white noise. We obtain for such a potential the same relationship between effective diffusion coefficient of Brownian particles and the mean first-passage time, discovered previously for fixed periodic potential (see ref. 3). The phenomenon of diffusion acceleration in comparison with free particle case has been found for arbitrary potential profile. The effective diffusion coefficients for sawtooth, sinusoidal and piecewise parabolic potentials are calculated in closed analytical form.
We show that the increment of generalized Wiener process (random process with stationary and inde... more We show that the increment of generalized Wiener process (random process with stationary and independent increments) has the properties of a random value with infinitely divisible distribution. This enables us to write the characteristic function of increments and then to ...
Abstract The structure of the electron current through an individual filament of a nanometer-size... more Abstract The structure of the electron current through an individual filament of a nanometer-sized virtual memristor consisting of a contact of a conductive atomic force microscope probe to an yttria stabilized zirconia (YSZ) thin film deposited on a conductive substrate is investigated. Usually, such investigation is performed by the analysis of the waveform of this current with the aim to extract the random telegraph noise (RTN). Here, we suggest a new indirect method, which is based on the measurement of the spectrum of the low-frequency flicker noise in this current without extracting the RTN, taking into account the geometrical parameters of the filament. We propose that the flicker noise is caused by the motion (drift/diffusion) of oxygen ions via oxygen vacancies within and around the filament. This allows us to estimate the root mean square magnitude i0 of the current jumps, which are caused by random jumps of oxygen ions, and the number M of these ions. This is fundamental for understanding the elementary mechanisms of electron current flowing through the filament and resistive switching in YSZ–based memristor devices.
Journal of Statistical Mechanics: Theory and Experiment, Sep 2, 2019
We theoretically investigate the fluctuations in the number of emergent magnetic monopoles in spi... more We theoretically investigate the fluctuations in the number of emergent magnetic monopoles in spin ice. The Langevin equation for these fluctuations is deduced. That allows us to calculate the spectrum of relative fluctuations, which can be measured experimentally. Keywords—magnetic monopoles; spin ice; fluctuations; ice rules; generation-recombination.
The results of the experimental investigation of the relationship between the low-frequency noise... more The results of the experimental investigation of the relationship between the low-frequency noise spectrum of the electric current through conducting filaments in Si3N4 films with a thickness of 6 nm on n ++-Si(001) conducting substrates and retention characteristics of these filaments are reported. Two structures are investigated: Si3N4/Si, thin (about 6 nm) Si3N4 film on the n++-Si substrate; Si3N4/SiO2/Si, a similar structure with a 2 nm SiO2 sublayer between the film and the substrate. A detailed comparison of the experimentally extracted parameters, such as average current through the filament, probability density function, and spectrum, is presented with a discussion of possible physical reasons for the difference between the testing structures and their effect on retention characteristics.
Resistive memories are outstanding electron devices that have displayed a large potential in a pl... more 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: stochast...
Here we summarize some relevant results related to nonequilibrium phenomena in mesoscopic and qua... more Here we summarize some relevant results related to nonequilibrium phenomena in mesoscopic and quantum systems. A common phenomenon in the dynamics of out-of-equilibrium systems is the metastability, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. Metastability (see Fig. 1) is a signature of a first order phase transition, often characterized by a long-living metastable state. In particular, the stability of a metastable state can be enhanced by Gaussian and non-Gaussian noise sources. This counterintuitive effect has been found in different physical areas, ranging from spintronics, aggregation kinetics of Brownian particles, Josephson junction systems, to interdisciplinary physical models
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