Related papers: Crystal structure effects on vortex dynamics in su…
Vortex dynamics is strongly connected with the mechanisms responsible for the photon detection of superconducting devices. Indeed, the local suppression of superconductivity by photon absorption may trigger vortex nucleation and motion…
Current-voltage (I-V) characteristics of quench condensed, superconducting, ultrathin $Bi$ films in a magnetic field are reported. These I-V's show hysteresis for all films, grown both with and without thin $Ge$ underlayers. Films on Ge…
The work reported in my doctoral thesis is an experimental study of vortex dynamics and phase transitions in thin films of type II superconductors using scanning tunneling spectroscopy, low frequency ac susceptibility measurements and…
In a small subset of type II superconductor films, the critical current is determined by a weakened Bean-Livingston barrier posed by the film surfaces to vortex penetration into the sample. A film property thus depends sensitively on the…
We have performed flux noise and AC-susceptibility measurements on two 400 nm thick MgB$_2$ films. Both measurement techniques give information about the vortex dynamics in the sample, and hence the superconducting transition, and can be…
The effects of Fe-ion irradiation on the crystal structure and superconducting properties of MgB$_2$ thin films were investigated. Pristine samples were prepared using hybrid physical-chemical vapor deposition (HPCVD), and ion irradiation…
Current-voltage (I-V) characteristics of quench condensed, superconducting, ultrathin Bi films in a magnetic field are reported. These show hysteresis for all films, grown both with and without thin Ge underlayers. Films on Ge underlayers,…
The current-voltage (I-V) characteristics of various MgB2 films have been studied at different magnetic fields parallel to c-axis. At fields \mu0H between 0 and 5T, vortex liquid-glass transitions were found in the I-V isotherms.…
The fragile-to-strong glass transition is a fascinating phenomenon that still presents many theoretical and experimental challenges. A major one is how to tune the fragility of a glass-forming liquid. Here, we study a two-dimensional (2D)…
In this thesis, we have studied the evolution of superconductivity in amorphous Molybdenum Germanium ($\textit{a}$-MoGe) thin films. The work can be broken down into two parts. In the first part, we investigate the effect of decreasing…
We study the distribution of transport current across superconducting Bi$_2$Sr$_2$CaCu$_2$O$_8$ crystals and the vortex flow through the sample edges. We show that the $T_x$ transition is of electrodynamic rather than thermodynamic nature,…
The effect of fractal normal-phase clusters on vortex dynamics in a percolative superconductor is considered. The superconductor contains percolative superconducting cluster carrying a transport current and clusters of a normal phase,…
The flux flow resistivity associated with purely viscous motion of vortices in high-quality MgB_2 was measured by microwave surface impedance. Flux flow resistivity exhibits unusual field dependence with strong enhancement at low field,…
A new class of artificial atoms, such as synthetic nanocrystals or vortices in superconductors, naturally self-assemble into ordered arrays. This property makes them applicable to the design of novel solids, and devices whose properties…
Thickness uniformity is regarded as an important parameter in designing thin film devices. However, some applications based on films with non-uniform thickness have recently emerged, such as gas sensors and optimized materials based on the…
We report the influence of intrinsic superconducting parameters on the vortex dynamics and the critical current densities of a MgB$_2$ thin film. The small magnetic penetration depth of \lambda = 50 nm at T=4 K is related to a clean…
An one-dimensional model of magnetic flux penetration into thin strip-like superconductive film is subject to numerical analysis which combines explicit account for specific oblate geometry of magnetic field lines around the film and a…
The observance of vortex and anti-vortex effects in bulk crystals can prove the existence of phase-disordered superconductivity in the bulk. To gain insights into the mechanisms that govern superconducting transition in copper oxide…
Interactions between vortices in thin superconducting films are investigated in the crossover (intertype) regime between superconductivity types I and II. We consider two main factors responsible for this crossover: a) changes in the…
V(I) characteristics have been performed in a monocrystalline microbridge of $Bi[Pb]-2212$. The vortex phase diagram has been greatly investigated. Linear but non-ohmic Voltage(Current) (V(I)) curves with well defined critical current have…