Sergey Savel’ev

Transport and localization in periodic and disordered graphene superlattices

We study the transport of low-energy charged quasiparticles in graphene superlattices created by applying either periodic or disordered smooth scalar potentials, which cause no intervalley scattering. It is shown that the transport and spectral properties of such structures are strongly anisotropic. In the direction perpendicular to the layers, the eigenstates in a disordered sample are delocalized for all energies and provide a minimum nonzero conductivity, which cannot be destroyed by disorder, no matter how strong this is. However, along with extended states, there exist discrete sets of angles and energies with exponentially localized eigenfunctions (disorder-induced resonances). Owing to these features, such samples could be used as building blocks in tunable electronic circuits. It is shown that, depending on the type of the unperturbed system, the disorder could either suppress or enhance the transmission. Remarkable properties of the transmission have been found in graphene systems built of alternating

Generation of tunable terahertz out-of-plane radiation using Josephson vortices in modulated layered superconductors

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Massless Dirac fermions in a laser field as a counterpart of graphene superlattices

and

A novel true random number generator based on a stochastic diffusive memristor

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Controlling the motion of interacting particles: Homogeneous systems and binary mixtures

junctions. The mean transmission coefficient has anomalously narrow angular spectrum, practically independent of the amplitude of the fluctuations of the potential. To better understand the physical implications of the results presented here, most of these have been compared with the results for analogous electromagnetic wave systems. Along with similarities, a number of quite surprising differences have been found.

Relativistic Brownian motion on a graphene chip

We show that a moving Josephson vortex in spatially modulated layered superconductors generates out-of-plane THz radiation. Remarkably, the magnetic and in-plane electric fields radiated are of the same order, which is very unusual for any good-conducting medium. Therefore, the out-of-plane radiation can be emitted to the vacuum without the standard impedance mismatch problem. Thus, the proposed tunable THz emitter for out-of-plane radiation can be more efficient than the standard one which radiates only along the

Surface plasma waves across the layers of intrinsic Josephson junctions

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Chirality tunneling and quantum dynamics for domain walls in mesoscopic ferromagnets

-plane.

Quantum electromechanics: Quantum tunneling near resonance and qubits from buckling nanoscale bars

We establish an analogy between spectra of Dirac fermions in laser fields and an electron spectrum of graphene superlattices formed by static 1D periodic potentials. The general relations between a laser-controlled spectrum where electron momentum depends on the quasi-energy and a superlattice mini-band spectrum in graphene are derived. As an example we consider two spectra generated by a pulsed laser and by a step-like electrostatic potential. We also calculate the graphene excitation spectrum in continuous strong laser fields in the resonance approximation for linear and circular polarizations and show that circular polarized laser fields cannot be reduced to any graphene electrostatic superlattice. Some physical phenomena related to the peculiar graphene energy spectrum in the strong electromagnetic field are discussed.

Phase diagram in highly anisotropic layered superconductors: crossing lattice melting transitions

The intrinsic variability of switching behavior in memristors has been a major obstacle to their adoption as the next generation of universal memory. On the other hand, this natural stochasticity can be valuable for hardware security applications. Here we propose and demonstrate a novel true random number generator utilizing the stochastic delay time of threshold switching in a Ag:SiO2 diffusive memristor, which exhibits evident advantages in scalability, circuit complexity, and power consumption. The random bits generated by the diffusive memristor true random number generator pass all 15 NIST randomness tests without any post-processing, a first for memristive-switching true random number generators. Based on nanoparticle dynamic simulation and analytical estimates, we attribute the stochasticity in delay time to the probabilistic process by which Ag particles detach from a Ag reservoir. This work paves the way for memristors in hardware security applications for the era of the Internet of Things.Memristors can switch between high and low electrical-resistance states, but the switching behaviour can be unpredictable. Here, the authors harness this unpredictability to develop a memristor-based true random number generator that uses the stochastic delay time of threshold switching