Related papers: Phase fluctuations in finite thickness disordered …
We measure the frequency dependence of the complex ac conductivity of NbN films with different levels of disorder in frequency range 0.4-20 GHz. Films with low disorder exhibit a narrow dynamic fluctuation regime above T_c as expected for a…
The effect of fluctuation induced weakly first order phase transition known for three dimensional (3D) type I superconductors appears in a modified and strongly enhanced variant in thin (quasi-2D) superconducting films. The unusual…
Properties of disordered thin films are discussed based on the viewpoint that superconducting islands are formed in the system. These lead to superconducting correlations confined in space, which are known to form spontaneously in thin…
We report a comprehensive study of the complex AC conductance of amorphous superconducting InO$_x$ thin films. Using a novel broadband microwave `Corbino' spectrometer we measure the explicit frequency dependency of the complex conductance…
It is shown that transition from the mixed state without the phase coherence to the mixed state with the long-range phase coherence (i.e. to the Abrikosov state) of superconductors without disorder must be first order phase transition. The…
Disordered thin films close to the superconducting-insulating phase transition (SIT) hold the key to understanding quantum phase transition in strongly correlated materials. The SIT is governed by superconducting quantum fluctuations, which…
We present transport, Hall effect, electronic tunnelling and penetration depth studies in 3D homogeneously disordered epitaxial NbN thin films with disorder ranging from the moderately clean limit (k_Fl~10.12) to the very dirty limit…
The complex ac conductivity of thin highly disordered InOx films was studied as a function of magnetic field through the nominal two-dimensional superconductor-insulator transition. We have resolved a significant finite-frequency superfluid…
Understanding the roles of disorder and superconducting phase fluctuation in superconductivity has been a long-standing challenge. For example, while the phase fluctuation is expected to destroy the superconductivity of intrinsically…
As a part of my doctoral thesis, I studied the effect of phase fluctuations in two dimensional (2D) and three dimensional (3D) superconducting films of conventional s-wave superconductor, NbN, by measuring the electrodynamics response…
We review our recent measurements of the complex AC conductivity of thin InO_x films studied as a function of magnetic field through the nominal 2D superconductor-insulator transition. These measurements - the first of their type to probe…
A new approach to the treatment of magnetic fluctuations in thin films of type I superconductors is introduced. Results for the dependence of free energy, specific heat and order parameter profile on the film thickness near the equilibrium…
Competing phenomena in low dimensional systems can generate exotic electronic phases, either through symmetry breaking or a non-trivial topology. In two-dimensional (2D) systems, the interplay between superfluidity, disorder and repulsive…
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…
As a superconducting thin film becomes disordered and subject to an increasing magnetic field, a point is reached when it undergoes a transition from a superconducting to an insulating state. We use the Bogoliubov-De-Gennes equations and a…
We investigate the evolution of superconductivity with decreasing film thickness in ultrathin amorphous MoGe (a-MoGe) films using a combination of sub-Kelvin scanning tunneling spectroscopy, magnetic penetration depth measurements and…
We consider a two-dimensional disordered conductor in the regime when the superconducting phase is destroyed by the magnetic field. We analyze a combination of fluctuations of different origin which results in an effective interaction…
Near the superconducting phase transition, fluctuations significantly modify the electronic transport properties. Here we study the fluctuation corrections to the Hall conductivity in disordered films, extending previous derivations to a…
We study theoretically orbital effects of a parallel magnetic field applied to a disordered superconducting film. We find that the field reduces the phase stiffness and leads to strong quantum phase fluctuations driving the system into an…
DC and finite frequency transport measurements of thin films of amorphous indium oxide that were driven through the critical point of superconductor-insulator transition by the application of perpendicular magnetic field are presented. The…