We numerically examine vortices interacting with pinning arrays where a portion of the pinning sites have been removed in order to create coexisting regions of strong and weak pinning. The region without pinning sites acts as an easy-flow channel. For driving in different directions with respect to the channel, we observe distinct types of vortex flow. When the drive is parallel to the channel, the

Here we describe the development of a computer algorithm to simulate the Time-Dependent Ginzburg-Landau equation (TDGL) and its application to understand superconducting vortex dynamics in confined geometries. Our initial motivation to get involved in this task was trying to understand better our experimental measurements on the dynamics of superconductors with vortices at high frequencies leading

The effect of the magnetic field renormalization in superconducting nanostructured materials is quantitatively evaluated. For demonstration purposes, three superconducting structures with various geometric shapes and dimensions and functioning in different resistive regimes are considered. Simulation is based on a set of equations including the time-dependent Ginzburg-Landau equation coupled with the

The angular dependence of magnetic-field commensurability effects in thin films of the cuprate high-critical-temperature superconductor YBa2Cu3O7−δ (YBCO) with an artificial pinning landscape is investigated. Columns of point defects are fabricated by two different methods of ion irradiation — scanning the focused 30 keV ion beam in a helium ion microscope or employing the wide-field 75 keV He+ beam

Dependence of the critical current on the misorientation angle in high-temperature superconductor (HTS) [001]-tilt bicrystal is theoretically examined. It’s argued that in the case of relatively small values of the bicrystal misorientation angle θ (θ ≤ 10–15°) the critical current as well as the resistive state emergence are determined by depinning of Abrikosov vortices, which are locked by c-oriented

In this paper we present a short overview on the results that can be obtained through the study of vortex motion at high frequencies. The phenomenological force balance for isolated-like vortices shaken by microwave currents and subjected to viscous drag, pinning forces and thermal creep is recalled and physically presented. The derived vortex motion resistivity, together with the main vortex parameters

In this paper we present an overview of the microwave properties of a surface electromagnetic wave resonator (SEWR) made on the basis of a superconducting film, and also consider possible applications of such resonators to create various microwave devices. Features of such a SEWR are the simplicity of its design (such a resonator, in fact, can be just the superconducting film itself on a dielectric

Within the framework of the proposed generalization of the phenomenological model of a microwave nonlinear HTSC transmission line, the effects of direct current on the transmission line are studied. Taking into account the next term in the expansion of the nonlinear dependence of the resistance on current allows us to explain the anomalous dependence of the insertion loss on the input power level observed

Technological applications of NbN thin films may be threatened by the development of magnetic flux avalanches of thermomagnetic origin appearing in a large portion of the superconducting phase. In this work, we describe an approach to substantially suppress the magnetic flux avalanche regime, without compromising the upper critical field. This procedure consists of depositing a thin Nb layer before

We discuss two possible mechanisms of the flux flow instability (FFI) in type II superconducting strips. While the nature of nonequilibrium effects leading to this instability is widely accepted (Joule heating and finite relaxation time of the superconducting order parameter) still there is a question how FFI develops in space. According to one scenario instability occurs simultaneously in the whole

We have studied vortex dynamics in superconducting materials at very high vortex velocities as a function of the applied magnetic field. High velocity vortex dynamics can become critical, so that an instability occurs, leading the system to quench abruptly to the normal state. The presence of pinning mechanisms in all superconductors not only is able to foster high critical currents but it can strongly

Ultrathin microstrips based on polycrystalline NbRe films were investigated in order to preliminarily test the suitability of this material for the realization of superconducting single-photon detectors. The voltage-current characteristics measured on these samples show clear hysteresis. This is a fundamental ingredient for investigating single-photon detection as well as single vortex fluctuation

Nowadays, the interaction between phonon and magnon subsystems of a magnetic medium is a hot topic of research. The complexity of phonon and magnon spectra, the existence of both bulk and surface modes, the quantization effects, and the dependence of magnon properties on applied magnetic field, make this field very complex and intriguing. Moreover, the recent advances in the fields of spin caloritronics

Conductance-voltage characteristics (CVCs) of tunnel break junctions made of Bi2Sr2CaCu2O8+δ crystals were measured. It was demonstrated that the CVCs have a V-shaped inner gap region, similar to those typical of CVCs for tunnel junctions between d-wave superconductors. The CVCs have different forms for different junctions, but all of them reveal weak dip-hump structures outside the inner gap region

A short overview of theoretical models for the description of the relaxation processes in metals excited by a short laser pulse is presented. The main effort is given to description of different processes which are taking place after absorption of the laser pulse. Widely used two-temperature model is discussed and the conditions of applicability of this model are identified. Various approaches for

Crossed electric and magnetic fields influence dipolar neutral particles in the same way as the magnetic field influences charged particles. The effect of crossed fields is proportional to the dipole moment of the particle (inherent or induced). We show that this effect is quite spectacular in a multilayer system of polar molecules. In this system molecules may bind in chains. At low temperature the

The current in a superconducting closed loop containing a thin-film interferometer with two point contacts (two Josephson-type weak links) has been measured as a function of the transport current and external magnetic field applied to interferometer. The differences between the transport and magnetic dependences of the system under study and similar characteristics for a superconducting closed loop

The review is focused on our predictions of nontrivial physical phenomena taking place in the nanostructure single-layer graphene on ferroelectric substrate, which are related with magnetic field. In particular we predicted that 180-degree domain walls in a strained ferroelectric film can induce p-n junctions in a graphene channel and lead to the unusual temperature and gate voltage dependences of

The paper presents a brief review of the recent developments in the field of absorption of atomic and molecular species in carbon cellular structures. Such absorbing objects can be distinctly recognized among a large family of carbon porous materials owing to potential and already observed in experiments very high capacity to soak and to keep inside different substances, which at usual conditions outside

The densities of phonon states and their related vibrational thermodynamic characteristics, such as heat capacity, root-mean-square displacement of atoms, and thermal expansion, are calculated and analyzed at the microscopic level for graphite and graphene nanoformations, such as nanofilms and nanotubes. The simulation model is based on experimental data without a priori assumptions as to the nature

The electronic spectrum of graphene with a single point impurity is considered. Local densities of states at the impurity site and its nearest neighbors are calculated analytically. Their evolution with increasing the impurity potential is examined. It is shown that in the domain of the well-defined impurity resonance the local density of states at the first-nearest neighbor of the impurity site is

We obtain a general expression for the differential entropy per particle (DEP) for three-dimensional Dirac systems as a function of chemical potential, temperature and magnetic field. It is shown that in the presence of magnetic field the dependence of DEP on the chemical potential near a charge neutral point is quite different from the corresponding dependence in graphene. Specifically, we observe

The functionalization (adsorption) of graphene and carbon nanotubes (CNT) is investigated in the case of charge transfer between a functionalizing molecule (adatom) and a substrate (graphenes or CNT), and the first principles charge transfer calculations are briefly reviewed. It is shown that electrostatic dipoles caused by charge transfer describe the interaction between the adsorbed atoms or islands

The authors have studied the effect of small (≤ 1 wt%) additions of thermally reduced graphene oxide on the microhardness and microindentation kinetics in two types of polymers: polystyrene (i.e. thermoplastic with a glass transition temperature of Tg ≈ 373 K) and polyester resin (i.e. thermosetting plastic, Tg ≈ 300 K). The room temperature creep of nanocomposites under an indenter is described using

Temperature dependences of electrical conductivity of reduced graphene oxide composite with single-walled nanotubes (rGO-SWNTs) and rGO films has been studied in the temperature range of 25–290 K. Both films were obtained by vacuum filtration of aqueous suspensions. Temperature dependences of conductivity of films were found similar to the conductivity observed in disordered semiconducting systems

Scanning electron microscopy, X-ray diffraction, and thermoprogrammed desorption methods were used to study the effect of treatment with a pulsed high-frequency discharge in a hydrogen atmosphere on the morphology, structure, and sorption characteristics of thermally reduced graphene oxide (TRGO). The TRGO treatment with pulsed gas discharge was shown to enhance the physical sorption of hydrogen by

Measurements of heat capacity at constant pressure of thermally reduced graphene oxide (trGO) and graphite oxide (GtO) were performed in the temperature range from 1.8 to 275 K by thermal relaxation method. Above 15 K, the specific heat values of trGO and GtO are close to each other within 20%. Below 10 K, the ratio of the specific heat of trGO to the specific heat of GtO increases with decreasing