Related papers: The critical current of YBa2Cu3O7-d Low Angle Grai…
An exact analytical solution is given for the critical state problem in long thin superconductor strips in a perpendicular magnetic field, when the critical current density j_c(B) depends on the local induction B according to a simple…
The charge redistribution at grain boundaries determines the applicability of high-Tc superconductors in electronic devices, because the transport across the grains can be hindered considerably. We investigate the local charge transfer and…
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…
We measured unusual critical currents as functions of temperature in the zero field and as functions of a magnetic field perpendicular to the substrate surface at a given temperature close to the critical temperature in thin-film long…
We report on measurements of the doping dependence of the upper critical field $H_{c,2}$ in 50 nm thick YBa$_2$Cu$_3$O$_{7-\delta}$ films. The films are untwinned and are characterized by a small in-plane compressive strain. We find that…
We present the latest generation of superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions with a step-like thickness of the ferromagnetic (F) layer. The F-layer thicknesses $d_1$ and $d_2$ in both halves were varied…
122 type pnictide superconductors are of particular interest for high-field applications because of their large upper critical fields Hc2 (> 100 T), low Hc2 anisotropy r (< 2), and high thin-film critical current densities Jc (> 1 MA/cm2 at…
Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d are presented. The samples were cut out of centimetric monoliths. Films characteristics were also measured on microbridges patterned on thin films grown by dc…
Spectral features induced by 45$^{\circ }$ in-plane misoriented grains have been observed in the far infrared magneto-transmission of YBa$_2$Cu$_3$O$% _{7-\delta }$ thin films. Two strong dispersive features are found at 80 and 160…
The case of ac transport at in-phase alternating applied magnetic fields for a superconducting rectangular strip with finite thickness has been investigated. The applied magnetic field is considered perpendicular to the current flow. We…
A series of polycrystalline SmO1-xFxFeAs bulks (x=0.15, 0.2, 0.3 and 0.4) were prepared by the conventional solid state reaction. Resistivity, susceptibility, magnetic hysteresis, critical current density and microstructure of these samples…
We report measurements of the flux hysteresis curves and trapped flux distribution in an YBa2Cu3O7 r.f. SQUID containing two closely spaced grain boundary Josephson junctions in parallel. Broadening of the flux distribution from T = 15 K to…
We have fabricated a series of ex situ copper sheathed powder-in-tube MgB2 wires with 20% by volume Ag, Pb, In, and Ga metal added to the MgB2 powder. We find the transport critical current of these wires increases significantly with the…
Ubiquitous in most superconducting materials and a common result of nanofabrication processes, weak-links are known for their limiting effects on the transport of electric currents. Still, they are at the root of key features of…
For many applications of polycrystalline high-Tc superconductors the small critical currents of the grain boundaries pose a severe problem. To solve this problem we derive novel designs for the microstructure of coated conductors.
The critical current density (Jc) through a superconductor in high magnetic fields is controlled by the inclusions and microstructure of the material that hold fluxons stationary to keep the resistance zero and is described using…
We investigate the influence of Pearl vortices in the vicinity of an edge-type Josephson junction for a superconducting thin-film loop in the form of an annulus, under uniform magnetic field. Specifically, we obtain the exact analytic…
Transport measurements in ramp-type junctions of $YBa_2Cu_3O_y-SrRuO_3-YBa_2Cu_3O_y$ with $T_c$ values of either 80-90 K or 60-70 K are reported. In both type of junctions but without a barrier ("shorts"), the supercurrent densities at 4.2…
\\A simple model for a superconductor with tunable critical current is studied theoretically. The model consists of a thin superconducting film with one vortex interacting with one magnetic dipole, whose magnetic moment is free to rotate,…
We have measured magnetic response of second-generation high temperature superconductor YBa2Cu3Ox wire and Nb thin film in perpendicular ac field as a function of temperature. We compare experimental complex ac susceptibility to the…