We present a phenomenological description of the high-frequency vortex dynamics in and discuss main parameters related to motion, namely viscous drag coefficient , pinning constant (Labusch parameter) depinning frequency . demonstrate experimental results on angular temperature dependence compare these with existing models. show how studies viscosity may yield information superclean limit. This limit corresponds formation discrete excitation spectrum core due quantum confinement small...

We have used the parallel-plate resonator technique to study microwave surface resistance ${\mathit{R}}_{\mathit{s}}$ and penetration depth \ensuremath{\lambda} of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$ thin epitaxial films at 5.5 GHz in presence magnetic field H\ensuremath{\le}0.8 T 30 KT80 K. The magnetic-field dependence allows determination vortex viscosity \ensuremath{\eta}, pinning constant \ensuremath{\alpha}, depinning frequency...

We report on magnetic susceptibility, NMR, and EPR measurements of pristine Fe-doped micro- nanosized graphenes (LGr NGr), prepared by a unique microwave enabled technique from graphite particles. Significant orbital diamagnetism in the studied compounds (∼70% that bulk graphite) is revealed. At T < 30 K, weak paramagnetism due to edge π-electronic spin states observed. Reduction lateral size graphene sheets results suppression strengthening paramagnetic contribution an increased number open...

Ferromagnetic and transport properties of ${\mathrm{La}}_{0.8}{\mathrm{Ca}}_{0.2}{\mathrm{MnO}}_{3}$ ${\mathrm{La}}_{0.78}{\mathrm{Ca}}_{0.22}{\mathrm{MnO}}_{3}$ single crystals were studied in temperature range $4.2\mathrm{K}&lt;T&lt;300\mathrm{K}$ under hydrostatic pressure up to 12 kbar. It was found that the above compounds exhibit different shifts Curie temperatures ${T}_{C}$ pressure. For ${\mathrm{dT}}_{C}/dP\ensuremath{\approx}0.3\mathrm{K}/\mathrm{k}\mathrm{b}\mathrm{a}\mathrm{r},$...

Most of superconductors in a magnetic field are penetrated by lattice quantized flux vortices. In the presence transport current causing vortices to cross sample edges, emission electromagnetic waves is expected due continuity tangential components fields at surface. Yet, such radiation has not been observed so far low radiated power levels and lacking coherence vortex motion. Here, we report from crossing layers superconductor/insulator Mo/Si superlattice. The spectra consist narrow...

Bulk and surface properties of high-quality single crystals zirconium dodecaboride have been studied in the temperature range from $4.5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ up to superconducting transition temperature, which is found be nearly $6.06\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Scanning tunneling spectroscopy data, together with $\mathrm{dc}$ $\mathrm{ac}$ magnetization measurements, are consistent conventional $s$-wave pairing scenario, whereas they disagree estimates...

We report on the low-frequency dynamics of surface superconducting states in yttrium hexaboride single crystal. Tunneling and dc magnetization experiments demonstrate that ${\text{YB}}_{6}$ is a classical type-II BCS superconductor with slightly suppressed order parameter near surface. The ac response at frequencies 10--1500 Hz has been measured for fields ${H}_{0}$ parallel to crystal found ${H}_{0}>{H}_{c2}$ magnetic moment completely disappeared, while exhibited presence...

X-band electron magnetic resonance and dc/ac measurements have been employed to study the effects of chemical disorder on ordering in bulk nanometer-sized single crystals ceramics optimally-doped La0.7Ca0.3MnO3 manganite. The ground state samples appeared be ferromagnetic with lower Curie temperature higher homogeneity vicinity ferromagnetic-paramagnetic phase transition crystal, as compared those characteristics ceramics. influence technological driven “macroscopic” fluctuations Ca-dopant...

A lattice of Abrikosov vortices in type II superconductors is characterized by a periodic modulation the magnetic induction perpendicular to applied field. For coherent vortex motion under action transport current, at given point sample varies time with washboard frequency fWB = v/d, where v velocity and d distance between direction motion. Here, using spectrum analyzer connected 50 nm-wide Au nanowire meander near surface superconducting Nb film, we detect an ac voltage induced coherently...

We have studied the effect of chopped laser irradiation (λL=514 nm) on resonant frequency (f0≊5.4 GHz) a superconducting parallel-plate resonator (PPR) consisting two thin epitaxial YBa2Cu3O7−x films. demonstrate that shifts PPR with negligible change quality factor. Photoinduced deviation f0 strongly depends chopping and increases linearly light intensity. The illumination is attributed to photoinduced kinetic inductance due heating. This may be used produce phase modulation transmission lines.

A large nonlinear response of a single crystal ${\mathrm{ZrB}}_{12}$ to an ac field (frequency $40--2500\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$) for ${H}_{0}>{H}_{c2}$ has been observed. Direct measurements the wave form and exact numerical solution Ginzburg-Landau equations, as well phenomenological relaxation equation, permit study surface superconducting state dynamics. It is shown that low-frequency defined by transitions between metastable states under action field. The rate determines...

AC and dc magnetic measurements in temperature interval 5-350 K at external field H les 5 T were employed to probe the finite-size nonstoichiometry effects on ordering of La <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Ca MnO xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> half-doped manganite compound. It is shown that complex mixed bulk samples appears be unstable regarding both effects. The strongest one size effect,...

We report experimental studies of the low-frequency electrodynamics ${\mathrm{ZrB}}_{12}$ and Nb single crystals. The ac susceptibility at frequencies $3--1000\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ has been measured under a dc magnetic field ${H}_{0}$ applied parallel to sample surface. In surface superconducting state for several real part exhibits logarithmic frequency dependence as spin-glass systems. Kramers-Kronig analysis data shows large losses ultralow...

We report the results of an experimental study dc and low-frequency magnetic properties a K${}_{0.8}$Fe${}_{2\ensuremath{-}y}$Se${}_{2}$ single crystal when field is applied parallel to $\mathbf{ab}$ plane. From data obtained, we deduce full H-T phase diagram, which consists all three ${H}_{c1}(T)$, ${H}_{c2}(T)$, ${H}_{c3}(T)$ critical magnetic-field plots. The two ${H}_{c1}(T)$ ${H}_{c2}(T)$ curves were obtained from measurements, whereas surface critical-field line was extracted by ac...

AC and DC magnetic measurements in temperature interval 5-300 K at external field Hles 5 T were employed to probe compare ordering bulk nanometer-sized (15plusmn2 nm) La <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</sub> Ca xmlns:xlink="http://www.w3.org/1999/xlink">0.3</sub> MnO xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single crystals. The respective Curie temperatures (T xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> )~239...

Continuous bead-free C-type cubic gadolinium oxide (Gd2O3) nanofibers 20-30 μm long and 40-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning technique. Dipole-dipole interaction of neighboring Gd3+ ions with large length-to-diameter aspect ratio results some kind superparamagnetic behavior: fibers are magnetized twice stronger than Gd2O3 powder. Being compared commercial Gd-DTPA/Magnevist®, diethyleneglycol-coated (Gd2O3-DEG) show high 1/T1 1/T2 proton...

We report the results of an experimental study dc and ac magnetic properties superconducting Nb thin-walled cylinders in parallel to axis fields. The magnetization curves at various temperatures are measured. Surprisingly, 4.5 K, for fields much lower than ${H}_{c1}$, avalanchelike jumps observed. position is not reproducible changes from one experiment another, resembling vortex lattice instabilities usually observed larger ${H}_{c1}$. At 6.5 measured become smooth. response constant swept...

We report an experimental and theoretical study of the linear nonlinear microwave impedance thin ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ films in a dc magnetic field different orientations. The measurements were done using parallel-plate resonator technique at 5.7 GHz, $21\mathrm{K}<T<80\mathrm{K},$ for $H<0.8\mathrm{T}.$ demonstrate that contributions to response from nonlinearity are almost additive our (excluding very low power). increase...

Critical current density, ac susceptibility (real part ) and magneto-optical (MO) imaging were used to characterize round wire tapes made from pre-reacted MgB2 powder by the powder-in-tube method. Magnetic measurements indicated existence of large-scale weak-link networks in cores as-deformed Ni/MgB2 Cu/MgB2 wires tapes. As-deformed samples showed a two-step transition versus T traces as evidence weak links tape core. The first heat treatment (HT) led sharp transition, very strong connection...

Optimally doped La(1.85)Sr(0.15)CuO(4) single crystals have been investigated by dc and ac magnetic measurements. These rectangular needle-like shapes with the long needle axis parallel to crystallographic c (c-crystal) or basal planes (a-crystal). In both crystals, temperature dependence of upper critical fields (H(C2)) surface field (H(C3)) were measured. The H-T phase diagram is presented. Close T(C) = 35 K, for c-crystal, γ(C) H(C3)(c)/H(C2)(c) 1.80(2), whereas a-crystal γ(a)...

Electron magnetic resonance and ac dc measurements in respective temperature intervals 75–600 5–300K were employed to probe compare ordering two manganite ceramics with close composition: La0.9Ca0.1MnO3 (La0.9Ca0.1)0.99MnO3. X-ray powder diffraction low field proved that lattice parameters Curie temperatures of both compounds are each other. However, susceptibility, high measurements, experiments have shown the (La0.9Ca0.1)0.99MnO3 sample is characterized by stronger ferromagnetic...