Related papers: Vortex-unbinding and finite-size effects in Tl2Ba2…
The temperature dependence of the nonlinear current-voltage ($I$-$V$) characteristics in highly underdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$ ($x=0.07$ and 0.08) thick films has been studied in both zero and perpendicular magnetic fields $H$.…
Current-voltage ($I-V$) characteristics and the increase of superconducting transition temperature $T_c$ as a function of the number of half-unit-cell layers $n$ are studied on Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta}$ thin films grown by…
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 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.…
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,…
We report on the normal-superconducting phase transition in thick $\mathrm{YBa_{2}Cu_{3}O_{7-\delta}}$ films in zero magnetic field. We find significant finite-size effects at low currents even in our thickest films ($d = 3200$ \AA). Using…
We show that the size effects radically affect the electric field-current ($E-I$) relation of superconducting films. We calculate $E(J)$ due to thermally-activated hopping of single vortices driven by current $I$ across the film in a…
In framework of Ginzburg-Landau model it is shown that narrow superconducting film with width w ~ 3-8 \xi(T) (\xi(T) is a temperature dependent coherence length) exhibits unusual transport properties. In the absence of bulk pinning its…
We measure current-voltage characteristics as function of magnetic field and temperature in Nb strips of different thickness and width. The instability voltage of the flux flow state related to the vortex critical velocity v* is studied and…
Magnetic susceptibility measurements of 3-4 ML Fe/W(001) ferromagnetic films demonstrate that this is a 2DXY system in which a finite-size Kosterlitz-Thouless (KT) transition occurs. The films are grown in ultrahigh vacuum and their…
Using micro-bridge technique, we have studied the vortex dynamics in a very low temperature region (i.e. T/Tc -> 0) of the B-T phase diagram of Bi_2Sr_2Ca_1Cu_2O_{8+\delta} single crystal. We distinguish two types of vortex dynamics near…
We report a comprehensive study of the complex AC conductivity of thin effectively 2D amorphous superconducting InO_x films at zero applied field. Below a temperature scale T_c0 where the superconducting order parameter amplitude becomes…
The Berezinskii-Kosterlitz-Thouless (BKT) transition in ultra-thin NbN films is investigated in the presence of weak perpendicular magnetic fields. A jump in the phase stiffness at the BKT transition is detected up to 5 G, while the BKT…
The nature of the superconducting transition in highly underdoped thick films of La$_{2-x}$Sr$_x$CuO$_4$ ($x=0.07$ and 0.08) has been investigated using the in-plane transport measurements. The contribution of superconducting fluctuations…
We analyze the occurrence of the Beresinkii-Kosterlitz-Thouless transition in thin films of NbN at various film thickness, by probing the effect of vortex fluctuations on the temperature dependence of the superfluid density below $T_{BKT}$…
We develop a theory for the vortex unbinding transition in homogeneously disordered superconducting films. This theory incorporates the effects of quantum, mesoscopic and thermal fluctuations stemming from length scales ranging from the…
Longitudinal and transverse voltages have been measured on thin films of MgB2 with different superconducting transition widths. The study has been performed in zero and non-zero external magnetic fields. The non-zero transverse voltage has…
A numerical study of the neutral two-dimensional (2D) lattice Coulomb gas is performed to examine dynamic scaling, finite size effects, and the dynamic critical exponent $z$ of the Kosterlitz-Thouless-Berezinskii transition. By studying…
We present a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless (BKT) transition in ultrathin strongly disordered NbN films. Measurements of resistance, current-voltage characteristics and kinetic inductance on the very same…
In Type II superconductors, the vortex lattice can exhibit "inverse melting," transitioning from a liquid to a crystalline solid as temperature increases. While recently observed via scanning tunneling microscopy in a 20 nm thick amorphous…