arXiv subjects

Alexander Khitun

Publications and source records attributed to Alexander Khitun.

At least 19 recordsLinked to original sources

arXiv2026

Magnonic Combinatorial Memory based on a network of coupled active ring circuits

Magnonic Combinatorial Memory (MCM) is a type of memory where the bits of information are encoded in the signal propagation paths in the network. In this work, we consider MCM based on the network of a coupled active ring circuit (ARC). Each circuit includes a broadband amplifier, a magnonic delay line, an adjustable frequency filter, an adjustable phase shifter, and a power detector. The coupling between the circuits is via spin waves propagating in the common delay line - ferrite film. There may or may not be auto-oscillations in the active ring circuits, depending on the combination of circuit parameters and circuit coupling. The address of MCM is defined as the combination of the states of the phase shifters and frequency filters, while the MCM state is defined as the presence/absence of the auto-oscillations. The coupling between the circuits is achieved by placing micromagnets on top of the ferrite film. The number of bits that can be encoded in the network increases quadratically with the number of coupled circuits. This scaling provides a fundamental advantage over conventional memory. We present experimental data obtained for three magnonic ARCs connected via a single-crystal yttrium iron garnet Y3Fe2(FeO4)3 (YIG) film. The data illustrate an example of encoding a 27-bit binary response pattern, corresponding to the 27 experimentally accessible phase combinations. The results demonstrate a robust operation of MCM with an On/Off ratio exceeding 30 dB at room temperature. The advantages and shortcomings of the proposed approach are discussed.

cond-mat.other↗

arXiv2026

Color-Rule-Function Encoding for Combinatorial Memory

Combinatorial memory is a class of memory in which information is encoded in the set of paths through a structured mesh. In this work, we introduce a systematic encoding framework, referred to as the Color-Rule-Function (CRF) approach, for representing information in combinatorial memory. The method consists of four key steps: selecting a sequence of paths in the mesh, assigning values (e.g., colors) to each cell, defining a set of rules based on the values encountered along each path, and constructing a Boolean function that determines the state of each path. . The coding procedure is illustrated by several examples. The design space scales of the CRF scale fundamentally faster compared to conventional memory. This apparent advantage arises from the use of rule-based and functional representations but is accompanied by increased hardware complexity. A possible hardware realization of the CRF framework is discussed. Importantly, the hardware overhead can be substantially reduced through the use of customized modules. The examples of the customized design are described in the text. The combination of CRF coding with customized module design may lead to a practical advantage in data storage density. According to the estimates, the data storage density may exceed Exabit per centimeter squared. A key problem that requires further investigation is related to the minimum Hamming distance between an arbitrary target bit sequence and the closest sequence realizable within the CRF framework under fixed hardware constraints.

cs.IT↗

arXiv2025

Magnonic Combinatorial Memory for High-density Data Storage

There is an urgent need to enhance the storage density of memory devices to accommodate the exponentially increasing amount of data generated by humankind. In this work, we describe Magnonic Combinatorial Memory (MCM), where the bits of information are stored in the signal propagation paths in the network. The number of paths among the elements of the network is much larger compared to the number of elements, which makes it possible to enhance the data storage density compared to conventional memory devices. MCM is an active ring circuit consisting of electric and magnonic parts. The electric part includes a broadband amplifier, phase shifters, and frequency filters. The magnonic part is a mesh of frequency-dependent elements. Signal propagation path(s) in the mesh depend on the amplitude/phase matching between the electric and magnetic parts. The operation of the MCM is described based on the network model, where information is encoded in the S-parameters of the network elements as well as in the element arrangement in the network. We present experimental data for MCM with a four-terminal magnonic element. The element consists of a single-crystal yttrium iron garnet Y3Fe2(FeO4)3 (YIG) film and magnets on top of the film. There are four micro antennas aimed to convert electromagnetic waves into spin waves and vice versa. One of the antennas is used as an input port while the other three are the output ports. Experimental data show the prominent dependence of the element S-parameters on the magnet arrangement. The number of possible arrangements scales factorially with the number of magnets. There is a number of bits that can be encoded into one magnet arrangement. The results demonstrate a robust operation of MCM with an On/Off ratio for path detection exceeding 50 dB at room temperature. Physical limits and practical constraints of MCM are also discussed.

cond-mat.other↗

arXiv2024

Three-plate graphene capacitor for high-density electric energy storage

Graphene possesses a unique combination of physical properties including high carrier mobility and high current density it can sustain. In contrast to bulk metals, graphene does not completely screen the external electrostatic field. In this work, we consider the possibility of utilizing these properties for building devices for high-density electric energy storage. We consider a three-plate parallel plate capacitor where the middle plate is made of graphene and negatively charged. The electric forces of attraction acting on the electrons on the middle plate are compensated as the electric fields on both sides of the plate are not screened. However, it brings the system to an unstable equilibrium state. To make system stable, we consider fast oscillations similar to ones in Kapitza pendulum. AC electric current through the middle graphene plane creates a magnetic field. In turn, Lorentz force squeezes moving electrons towards the center of the middle plane. We present the results of numerical modeling showing the effect of AC electric current on electron movement. According to the estimates, the pseudopotential produced by the AC current may exceed 60 eV at room temperature. Such a large value of the pseudopotential is due to the high mobility and large current density in graphene. The electric field intensity between the edge plates and the middle plate may exceed the breakdown value for a conventional double-plate parallel-plate capacitors leading to the increase in the electric energy storage. The electric breakdown of the graphene capacitor is limited by the mechanical strength of the side plates. It may be possible to enhance the volume electric energy density above the gasoline 34 MJ/L. We also describe possible experiments to validate this idea.

physics.app-ph↗

arXiv2023

Magnonic Combinatorial Memory

In this work, we consider a type of magnetic memory where information is encoded into the mutual arrangements of magnets. The device is an active ring circuit comprising magnetic and electronic parts connected in series. The electric part includes a broad-band amplifier, phase shifters, and attenuators. The magnetic part is a mesh of magnonic waveguides with magnets placed on the waveguide junctions. There are amplitude and phase conditions for auto-oscillations to occur in the active ring circuit. The frequency(s) of the auto-oscillation and spin wave propagation route(s) in the magnetic part depends on the mutual arrangement of magnets in the mesh. The propagation route is detected with a set of power sensors. The correlation between circuit parameters and spin wave route is the base of memory operation. The combination of input/output switches connecting electric and magnetic parts, and electric phase shifters constitute the memory address. The output of power sensors is the memory state. We present experimental data on the proof-of-the-concept experiments on the prototype with just three magnets placed on top of a single-crystal yttrium iron garnet Y3Fe2(FeO4)3 (YIG) film. The results demonstrate a robust operation with On/Off ratio for route detection exceeding 35 dB at room temperature. The number of propagation routes scales factorial with the size of the magnetic part. Coding information in propagation routes makes it possible to drastically increase the data storage density compared to conventional memory devices. MCM with just 25 magnets can store as much as 25! (10 Yotta) bits. Physical limits and constraints are also discussed.

physics.app-ph↗

arXiv2023

Traveling Salesman Problem solution using Magnonic Combinatorial Device

Traveling Salesman Problem (TSP) is a decision-making problem that is essential for a number of practical applications. Today, this problem is solved on digital computers exploiting Boolean-type architecture by checking one by one a number of possible routes. In this work, we describe a special type of hardware for the TSP solution. It is a magnonic combinatorial device comprising magnetic and electric parts connected in the active ring circuit. There is a number of possible propagation routes in the magnetic mesh made of phase shifters, frequency filters, and attenuators. The phase shifters mimic cities in TSP while the distance between the cities is encoded in the signal attenuation. The set of frequency filters makes the waves on different frequencies propagate through the different routes. The principle of operation is based on the classical wave superposition. There is a number of waves coming in all possible routes in parallel accumulating different phase shifts and amplitude damping. However, only the wave(s) that accumulates the certain phase shift will be amplified by the electric part. The amplification comes first to the waves that possess the minimum propagation losses. It makes this type of device suitable for TSP solution, where waves are similar to the salesmen traveling in all possible routes at a time. We present the results of numerical modeling illustrating the TSP solutions for four and six cities. Also, we present experimental data for the TSP solution with four cities.

cond-mat.dis-nn↗

arXiv2022

Micro magnet location using spin waves

In this work, we present experimental data demonstrating the feasibility of magnetic object location using spin waves. The test structure includes a Y$_3$Fe$_2$(FeO$_4$)$_3$) (YIG) film with four micro-antennas placed on the edges. A constant in-plane bias magnetic field is provided by NdFeB permanent magnet. Two antennas are used for spin wave excitation while the other two are used for the inductive voltage measurement. There are nine selected places for the magnet on the film. The magnet was subsequently placed in all nine positions and spin wave transmission and reflection were measured. The obtained experimental data show the difference in the output signal amplitude depending on the magnet position. All nine locations can be identified by the frequency and the amplitude of the absolute minimum in the output power. All experiments are accomplished at room temperature. Potentially, spin waves can be utilized for remote magnetic bit read-out. The disadvantages and physical constraints of this approach are also discussed.

physics.app-ph↗

arXiv2022

Combinatorial logic devices based on a multi-path active ring circuit

In this work, we describe a logic device in which an act of computation is associated with finding a path connecting input and output ports. The device is based on an active ring circuit comprising electric and magnetic parts. The electric part includes an amplifier, a phase shifter, and an attenuator. The magnetic part is a multi-port magnetic matrix comprising delay lines and frequency filters. Signals propagating on different paths may accumulate different phase shifts. Auto-oscillations occur in the circuit when the magnetic and electric parts match each other to meet the resonance amplitude and phase conditions. The system naturally searches for a resonance path that depends on the position of the electric phase shifter and amplification level. The path is detected by the set of power sensors. The proposed logic device can be used for solving a variety of computational problems. We present the results of numerical modeling illustrating prime factorization and finding the shortest path connected selected points on the mesh.

cs.ET↗

arXiv2021

Spin Wave Interference Detection via Inverse Spin Hall Effect

In this letter, we present experimental data demonstrating spin wave interference detection using spin Hall effect (ISHE). Two coherent spin waves are excited in a yttrium-iron garnet (YIG) waveguide by continuous microwave signals. The initial phase difference between the spin waves is controlled by the external phase shifter. The ISHE voltage is detected at a distance of 2 mm and 4 mm away from the spin wave generating antennae by an attached Pt layer. Experimental data show ISHE voltage oscillation as a function of the phase difference between the two interfering spin waves. This experiment demonstrates an intriguing possibility of using ISHE in spin wave logic circuit converting spin wave phase into an electric signal

cond-mat.mes-hall↗

arXiv2020

Quantum Computing without Quantum Computers: Database Search and Data Processing Using Classical Wave Superposition

Quantum computing is an emerging field of science which will eventually lead us to new and powerful logic devices with capabilities far beyond the limits of current transistor-based technology. There are certain types of problems which quantum computers can solve fundamentally faster than the tradition digital computers. There are quantum algorithms which require both superposition and entanglement (e.g. Shor algorithm). But neither the Grover algorithm nor the very first quantum algorithm due to Deutsch and Jozsa need entanglement. Is it possible to utilize classical wave superposition to speedup database search? This interesting question was analyzed by S. Lloyd. It was concluded that classical devices that rely on wave interference may provide the same speedup over classical digital devices as quantum devices. There were several experimental works using optical beam superposition for emulating Grover algorithm. It was concluded that the use of classical wave superposition comes with the cost of exponential increase of the resources. Since then, it is widely believed that the use of classical wave superposition for quantum algorithms is inevitably leading to an exponential resources overhead (number of devices, power consumption, precision requirements). In this work, we describe a classical Oracle machine which utilizes classical wave superposition for database search and data processing. We present experimental data on magnetic database search using spin wave superposition. The data show a fundamental speedup over the digital computers without any exponential resource overhead. We argue that in some cases the classical wave-based approach may provide the same speedup in database search as quantum computers.

quant-ph↗

arXiv2020

An entertaining physics: On the possibility of energy storage enhancement in electric capacitors using the compensational inductive electric field

In this work, we consider the possibility of energy storage enhancement in electric capacitors using the compensational method. The essence of the proposed approach is the use of inductive voltage V_ind to partially compensate the electrostatic voltage q/C produced by the electric charges on the capacitor plates. We hypothesize that it may be possible to increase the amount of charge stored on the plates before the breakdown and increase the energy stored in the capacitor using the compensational inductive voltage. There are several possible scenarios of manipulating the inductive voltage to increase the amount of energy released via the discharge. We also consider several electro-magnetic capacitors for practical utilization. Potentially, the energy per volume stored in a simple parallel plate capacitor may exceed the one of gasoline. The physical limits and technological shortcomings of the proposed approach are also discussed.

physics.app-ph↗

arXiv2019

Amplitude and Phase Noise of Magnons

The low-frequency amplitude and phase noise spectra of magnetization waves, i.e. magnons, was measured in the yttrium iron garnet (YIG) waveguides. This type of noise, which originates from the fluctuations of the physical properties of the YIG crystals, has to be taken into account in the design of YIG-based RF generators and magnonic devices for data processing, sensing and imaging applications. It was found that the amplitude noise level of magnons depends strongly on the power level, increasing sharply at the on-set of nonlinear dissipation. The noise spectra of both the amplitude and phase noise have the Lorentzian shape with the characteristic frequencies below 100 Hz.

physics.app-ph↗

arXiv2019

Brillouin-Mandelstam Spectroscopy of Stress-Modulated Spatially Confined Spin Waves in Ni Thin Films on Piezoelectric Heterostructures

We report results of micro-Brillouin-Mandelstam light scattering spectroscopy of thermal magnons in the two-phase synthetic multiferroic structure consisting of a piezoelectric (PMN-PT) substrate and a Ni thin film with the thickness of 64 nm. The experimental data reveal the first two modes of the perpendicular standing spin waves (PSSW) spatially confined across the Ni thin film. A theoretical analysis of the frequency dependence of the PSSW peaks on the external magnetic field reveals the asymmetric boundary condition, i.e. pinning, for variable magnetization at different surfaces of the Ni thin film. The strain field induced by applying DC voltage to PMN-PT substrate leads to a down shift of PSSW mode frequency owing to the magneto-elastic effect in Ni, and corresponding changes in the spin wave resonance conditions. The observed non-monotonic dependence of the PSSW frequency on DC voltage is related to an abrupt change of the pinning parameter at certain values of the voltage. The obtained results are important for understanding the thermal magnon spectrum in ferromagnetic films and development of the low-power spin-wave devices.

cond-mat.mtrl-sci↗

arXiv2016

Two-Dimensional Oscillatory Neural Network Based on Charge-Density-Wave Devices Operating at Room Temperature

We propose an oscillatory neural network implemented with two-dimensional tantalum disulfide devices operating in the change density wave regime at room temperature. An elementary cell of the network consists of two 1T-TaS2 devices connected in series. Such a cell has constant output and oscillatory states. All cells have the same bias voltage. There is constant current flowing through the cell in the constant output mode. The oscillations occur at a certain bias voltage due to the electrical-field driven metal-to-insulator transition owing to the changes in the charge density wave phase in the 1T-TaS2 channel. Two 1T-TaS2 devices oscillate out-of-phase where one of the devices is in the insulator phase while the other one is in the metallic state. The nearest-neighbor cells are coupled via graphene transistors. The cells are resistively coupled if the graphene transistor is in the On state while they are capacitively coupled if the transistor is in the Off state. The operation of the oscillatory neural network is simulated numerically for the 30x30 node network. The results of our numerical modeling show the formation of artificial vortexes and cellular-automata type data processing. The two-dimensional 1T-TaS2 devices, utilized in the network, offer a unique combination of properties such as scalability, high operational frequency, fast synchronization speed, and radiation hardness, which makes them promising for both consumer electronic and defense applications.

cs.ET↗

arXiv2014

Pattern Recognition with Magnonic Holographic Memory Device

In this work, we present experimental data demonstrating the possibility of using magnonic holographic devices for pattern recognition. The prototype eight-terminal device consists of a magnetic matrix with micro-antennas placed on the periphery of the matrix to excite and detect spin waves. The principle of operation is based on the effect of spin wave interference, which is similar to the operation of optical holographic devices. Input information is encoded in the phases of the spin waves generated on the several edges of the magnonic matrix, while the output corresponds to the amplitude of the inductive voltage produced by the interfering spin waves on the other side of the matrix. The level of the output voltage depends on the combination of the input phases as well as on the internal structure of the magnonic matrix. Experimental data collected for several magnonic matrixes show the unique output signatures in which maxima and minima correspond to specific input phase patterns. Potentially, magnonic holographic devices may provide a higher storage density compare to the optical counterparts due to a shorter wavelength and compatibility with conventional electronic devices. The challenges and shortcoming of the magnonic holographic devices are also discussed.

cond-mat.mes-hall↗

arXiv2013

On the Possibility of Reversible Magnonic Logic Gates

We propose and develop a concept of magnonic logic gates enabling reversible computing. The gates consist of passive elements: waveguides, cross-junctions and phase shifters. Logical 0 and 1 are encoded in the relative phase of the propagating spin wave packets (0 or π). The gates contain several possible trajectories for each packet to propagate from the input to the output. Re-direction of the spin wave packets among the possible trajectories is due to the interference in the magnetic cross-junctions. Two wave packets coming to the cross-junction in-phase propagate through the junction without reflection. Two packets coming out-of-phase to the junction are completely reflected back. The operation of the cross-junction is illustrated by numerical modeling. We estimate the power dissipation in the proposed circuits and the feasibility of cascading such magnetic devices in large circuits. The proposed gates may potentially provide a route to magnetic reversible logic circuitry with power dissipation less than kT per operation.

quant-ph↗

arXiv2013

Synthetic Multiferroic Interconnects for Magnetic Logic Circuits

In this work, we consider the possibility of using synthetic multiferroics comprising piezoelectric and magnetostrictive materials as an interconnect for nano magnetic logic circuits. The proposed interconnect resembles a parallel plate capacitor filled with a piezoelectric, where one of the plates is made of a magnetoelastic material. The operation of the interconnect is based on the effect of stress-mediated anisotropy modulation, where an electric field applied across the piezoelectric material produces stress, which, in turn, affects the anisotropy field in the magnetostrictive material. We present the results of numerical modeling illustrating signal propagation through the interconnect. The model combines electric and magnetic parts, where the electric part describes the distribution of an electric field through the piezoelectric and the magnetic part describes the change of magnetization in the magnetoelastic layer. The model is based on the Landau-Lifshitz-Gilbert equation with the electric field dependent anisotropy term included. The utilization of the electro-magnetic coupling makes it possible to amplify magnetic signal during its propagation via energy conversion from the electric to magnetic domains. Potentially, synthetic multiferroic interconnects can be implemented in a variety of spin-based devices ensuring reliable and low-energy consuming data transmission. According to the estimates, the group velocity of magnetic signals may be up to 100 km/s with energy dissipation less than aJ per bit per 100nm. The fundamental limits and practical shortcoming of the proposed approach are also discussed.

cond-mat.mtrl-sci↗

arXiv2011

Multi-Frequency Magnonic Logic Circuits for Parallel Data Processing

We describe and analyze magnonic logic circuits enabling parallel data processing on multiple frequencies. The circuits combine bi-stable (digital) input/output elements and an analog core. The data transmission and processing within the analog part is accomplished by the spin waves, where logic 0 and 1 are encoded into the phase of the propagating wave. The latter makes it possible to utilize a number of bit carrying frequencies as independent information channels. The operation of the magnonic logic circuits is illustrated by numerical modeling. We also present the estimates on the potential functional throughput enhancement and compare it with scaled CMOS. The described multi-frequency approach offers a fundamental advantage over the transistor-based circuitry and may provide an extra dimension for the Moor's law continuation. The shortcoming and potentials issues are also discussed.

cond-mat.other↗